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121-457: The design goals of XML emphasize simplicity, generality, and usability across the Internet . It is a textual data format with strong support via Unicode for different human languages . Although the design of XML focuses on documents, the language is widely used for the representation of arbitrary data structures , such as those used in web services . Several schema systems exist to aid in

242-461: A 32-bit number. IPv4 is the initial version used on the first generation of the Internet and is still in dominant use. It was designed in 1981 to address up to ≈4.3 billion (10 ) hosts. However, the explosive growth of the Internet has led to IPv4 address exhaustion , which entered its final stage in 2011, when the global IPv4 address allocation pool was exhausted. Because of the growth of

363-515: A 4G network. The limits that users face on accessing information via mobile applications coincide with a broader process of fragmentation of the Internet . Fragmentation restricts access to media content and tends to affect the poorest users the most. Zero-rating , the practice of Internet service providers allowing users free connectivity to access specific content or applications without cost, has offered opportunities to surmount economic hurdles but has also been accused by its critics as creating

484-459: A lingua franca for representing information. As a markup language , XML labels, categorizes, and structurally organizes information. XML tags represent the data structure and contain metadata . What is within the tags is data, encoded in the way the XML standard specifies. An additional XML schema (XSD) defines the necessary metadata for interpreting and validating XML. (This is also referred to as

605-612: A valid XML document as a well-formed XML document which also conforms to the rules of a Document Type Definition (DTD). In addition to being well formed, an XML document may be valid . This means that it contains a reference to a Document Type Definition (DTD), and that its elements and attributes are declared in that DTD and follow the grammatical rules for them that the DTD specifies. XML processors are classified as validating or non-validating depending on whether or not they check XML documents for validity. A processor that discovers

726-446: A "control picture" for any of these. There is also no well-known variation of Caret notation for them either. Some terminal emulators , including xterm , use OSC sequences for setting the window title and changing the colour palette. They may also support terminating an OSC sequence with BEL instead of ST. Kermit used APC to transmit commands. The ISO/IEC 2022 (ECMA-35) extension mechanism allowed escape sequences to change

847-559: A 7-bit environment, thus it was decided that no alternative character set could use them, and that these codes should be additional control codes, which become known as the C1 control codes . To allow a 7-bit environment to use these new controls, the sequences ESC @ through ESC _ were to be considered equivalent. The later ISO 8859 standards abandoned support for 7-bit codes, but preserved this range of control characters. The first C1 control code set to be registered for use with ISO 2022

968-517: A blog, or building a website involves little initial cost and many cost-free services are available. However, publishing and maintaining large, professional web sites with attractive, diverse and up-to-date information is still a difficult and expensive proposition. Many individuals and some companies and groups use web logs or blogs, which are largely used as easily being able to update online diaries. Some commercial organizations encourage staff to communicate advice in their areas of specialization in

1089-470: A broad array of electronic, wireless , and optical networking technologies. The Internet carries a vast range of information resources and services, such as the interlinked hypertext documents and applications of the World Wide Web (WWW), electronic mail , telephony , and file sharing . The origins of the Internet date back to research that enabled the time-sharing of computer resources,

1210-626: A collection of documents (web pages) and other web resources linked by hyperlinks and URLs . In the 1960s, computer scientists began developing systems for time-sharing of computer resources. J. C. R. Licklider proposed the idea of a universal network while working at Bolt Beranek & Newman and, later, leading the Information Processing Techniques Office (IPTO) at the Advanced Research Projects Agency (ARPA) of

1331-593: A designated pool of addresses set aside for each region. The National Telecommunications and Information Administration , an agency of the United States Department of Commerce , had final approval over changes to the DNS root zone until the IANA stewardship transition on 1 October 2016. The Internet Society (ISOC) was founded in 1992 with a mission to "assure the open development, evolution and use of

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1452-513: A framework known as the Internet protocol suite (also called TCP/IP , based on the first two components.) This is a suite of protocols that are ordered into a set of four conceptional layers by the scope of their operation, originally documented in RFC   1122 and RFC   1123 . At the top is the application layer , where communication is described in terms of the objects or data structures most appropriate for each application. For example,

1573-419: A larger market or even sell goods and services entirely online . Business-to-business and financial services on the Internet affect supply chains across entire industries. The Internet has no single centralized governance in either technological implementation or policies for access and usage; each constituent network sets its own policies. The overarching definitions of the two principal name spaces on

1694-554: A method so an 8-bit "extended ASCII" code could be converted to a corresponding 7-bit code, and vice versa . In a 7-bit environment, the Shift Out ( SO ) would change the meaning of the 96 bytes 0x20 through 0x7F (i.e. all but the C0 control codes), to be the characters that an 8-bit environment would print if it used the same code with the high bit set. This meant that the range 0x80 through 0x9F could not be printed in

1815-555: A more compact non-XML syntax; the two syntaxes are isomorphic and James Clark 's conversion tool— Trang —can convert between them without loss of information. RELAX NG has a simpler definition and validation framework than XML Schema, making it easier to use and implement. It also has the ability to use datatype framework plug-ins ; a RELAX NG schema author, for example, can require values in an XML document to conform to definitions in XML Schema Datatypes. Schematron

1936-479: A necessary extra character for the DEL character, 7F HEX or 01111111 BIN (needed to punch out all the holes on a paper tape and erase it). This large number of codes was desirable at the time, as multi-byte controls would require implementation of a state machine in the terminal, which was very difficult with contemporary electronics and mechanical terminals. Only a few codes have maintained their use: BEL, ESC, and

2057-597: A network into two or more networks is called subnetting . Computers that belong to a subnet are addressed with an identical most-significant bit -group in their IP addresses. This results in the logical division of an IP address into two fields, the network number or routing prefix and the rest field or host identifier . The rest field is an identifier for a specific host or network interface. The routing prefix may be expressed in Classless Inter-Domain Routing (CIDR) notation written as

2178-488: A node on a different subnetwork. Routing tables are maintained by manual configuration or automatically by routing protocols . End-nodes typically use a default route that points toward an ISP providing transit, while ISP routers use the Border Gateway Protocol to establish the most efficient routing across the complex connections of the global Internet. The default gateway is the node that serves as

2299-506: A rich datatyping system and allow for more detailed constraints on an XML document's logical structure. XSDs also use an XML-based format, which makes it possible to use ordinary XML tools to help process them. xs:schema element that defines a schema: RELAX NG (Regular Language for XML Next Generation) was initially specified by OASIS and is now a standard (Part 2: Regular-grammar-based validation of ISO/IEC 19757 – DSDL ). RELAX NG schemas may be written in either an XML based syntax or

2420-593: A shorthand for internetwork in RFC   675 , and later RFCs repeated this use. Cerf and Kahn credit Louis Pouzin and others with important influences on the resulting TCP/IP design. National PTTs and commercial providers developed the X.25 standard and deployed it on public data networks . Access to the ARPANET was expanded in 1981 when the National Science Foundation (NSF) funded

2541-470: A sign of future growth, 15 sites were connected to the young ARPANET by the end of 1971. These early years were documented in the 1972 film Computer Networks: The Heralds of Resource Sharing . Thereafter, the ARPANET gradually developed into a decentralized communications network, connecting remote centers and military bases in the United States. Other user networks and research networks, such as

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2662-596: A two-tiered Internet. To address the issues with zero-rating, an alternative model has emerged in the concept of 'equal rating' and is being tested in experiments by Mozilla and Orange in Africa. Equal rating prevents prioritization of one type of content and zero-rates all content up to a specified data cap. In a study published by Chatham House , 15 out of 19 countries researched in Latin America had some kind of hybrid or zero-rated product offered. Some countries in

2783-421: A validity error must be able to report it, but may continue normal processing. A DTD is an example of a schema or grammar . Since the initial publication of XML 1.0, there has been substantial work in the area of schema languages for XML. Such schema languages typically constrain the set of elements that may be used in a document, which attributes may be applied to them, the order in which they may appear, and

2904-466: A vast and diverse amount of online information. Compared to printed media, books, encyclopedias and traditional libraries, the World Wide Web has enabled the decentralization of information on a large scale. The Web has enabled individuals and organizations to publish ideas and information to a potentially large audience online at greatly reduced expense and time delay. Publishing a web page,

3025-500: A violation is required to report such errors and to cease normal processing. This policy, occasionally referred to as " draconian error handling", stands in notable contrast to the behavior of programs that process HTML , which are designed to produce a reasonable result even in the presence of severe markup errors. XML's policy in this area has been criticized as a violation of Postel's law ("Be conservative in what you send; be liberal in what you accept"). The XML specification defines

3146-527: A vocabulary to refer to the constructs within an XML document, but does not provide any guidance on how to access this information. A variety of APIs for accessing XML have been developed and used, and some have been standardized. Existing APIs for XML processing tend to fall into these categories: Stream-oriented facilities require less memory and, for certain tasks based on a linear traversal of an XML document, are faster and simpler than other alternatives. Tree-traversal and data-binding APIs typically require

3267-696: A web browser operates in a client–server application model and exchanges information with the HyperText Transfer Protocol (HTTP) and an application-germane data structure, such as the HyperText Markup Language (HTML). Below this top layer, the transport layer connects applications on different hosts with a logical channel through the network. It provides this service with a variety of possible characteristics, such as ordered, reliable delivery (TCP), and an unreliable datagram service (UDP). Underlying these layers are

3388-581: A wide variety of other Internet software may be installed from app stores . Internet usage by mobile and tablet devices exceeded desktop worldwide for the first time in October 2016. The International Telecommunication Union (ITU) estimated that, by the end of 2017, 48% of individual users regularly connect to the Internet, up from 34% in 2012. Mobile Internet connectivity has played an important role in expanding access in recent years, especially in Asia and

3509-547: Is a global network that comprises many voluntarily interconnected autonomous networks. It operates without a central governing body. The technical underpinning and standardization of the core protocols ( IPv4 and IPv6 ) is an activity of the Internet Engineering Task Force (IETF), a non-profit organization of loosely affiliated international participants that anyone may associate with by contributing technical expertise. To maintain interoperability,

3630-412: Is a lexical , event-driven API in which a document is read serially and its contents are reported as callbacks to various methods on a handler object of the user's design. SAX is fast and efficient to implement, but difficult to use for extracting information at random from the XML, since it tends to burden the application author with keeping track of what part of the document is being processed. It

3751-726: Is a language for making assertions about the presence or absence of patterns in an XML document. It typically uses XPath expressions. Schematron is now a standard (Part 3: Rule-based validation of ISO/IEC 19757 – DSDL ). DSDL (Document Schema Definition Languages) is a multi-part ISO/IEC standard (ISO/IEC 19757) that brings together a comprehensive set of small schema languages, each targeted at specific problems. DSDL includes RELAX NG full and compact syntax, Schematron assertion language, and languages for defining datatypes, character repertoire constraints, renaming and entity expansion, and namespace-based routing of document fragments to different validators. DSDL schema languages do not have

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3872-399: Is a large address block with 2 addresses, having a 32-bit routing prefix. For IPv4, a network may also be characterized by its subnet mask or netmask , which is the bitmask that when applied by a bitwise AND operation to any IP address in the network, yields the routing prefix. Subnet masks are also expressed in dot-decimal notation like an address. For example, 255.255.255.0 is

3993-457: Is a well-formed XML document including Chinese , Armenian and Cyrillic characters: The XML specification defines an XML document as a well-formed text, meaning that it satisfies a list of syntax rules provided in the specification. Some key points in the fairly lengthy list include: The definition of an XML document excludes texts that contain violations of well-formedness rules; they are simply not XML. An XML processor that encounters such

4114-545: Is an alias) and application/xml-dtd . They are used for transmitting raw XML files without exposing their internal semantics . RFC 7303 further recommends that XML-based languages be given media types ending in +xml , for example, image/svg+xml for SVG . Further guidelines for the use of XML in a networked context appear in RFC 3470 , also known as IETF BCP 70, a document covering many aspects of designing and deploying an XML-based language. XML has come into common use for

4235-498: Is better suited to situations in which certain types of information are always handled the same way, no matter where they occur in the document. Pull parsing treats the document as a series of items read in sequence using the iterator design pattern . This allows for writing of recursive descent parsers in which the structure of the code performing the parsing mirrors the structure of the XML being parsed, and intermediate parsed results can be used and accessed as local variables within

4356-494: Is necessary to allocate address space efficiently. Subnetting may also enhance routing efficiency or have advantages in network management when subnetworks are administratively controlled by different entities in a larger organization. Subnets may be arranged logically in a hierarchical architecture, partitioning an organization's network address space into a tree-like routing structure. Computers and routers use routing tables in their operating system to direct IP packets to reach

4477-489: Is not an exhaustive list of all the constructs that appear in XML; it provides an introduction to the key constructs most often encountered in day-to-day use. XML documents consist entirely of characters from the Unicode repertoire. Except for a small number of specifically excluded control characters , any character defined by Unicode may appear within the content of an XML document. XML includes facilities for identifying

4598-532: Is not directly interoperable by design with IPv4. In essence, it establishes a parallel version of the Internet not directly accessible with IPv4 software. Thus, translation facilities must exist for internetworking or nodes must have duplicate networking software for both networks. Essentially all modern computer operating systems support both versions of the Internet Protocol. Network infrastructure, however, has been lagging in this development. Aside from

4719-406: Is often accessed through high-performance content delivery networks . The World Wide Web is a global collection of documents , images , multimedia , applications, and other resources, logically interrelated by hyperlinks and referenced with Uniform Resource Identifiers (URIs), which provide a global system of named references. URIs symbolically identify services, web servers , databases, and

4840-535: Is the only character that is not permitted in any XML 1.1 document. The Unicode character set can be encoded into bytes for storage or transmission in a variety of different ways, called "encodings". Unicode itself defines encodings that cover the entire repertoire; well-known ones include UTF-8 (which the XML standard recommends using, without a BOM ) and UTF-16 . There are many other text encodings that predate Unicode, such as ASCII and various ISO/IEC 8859 ; their character repertoires are in every case subsets of

4961-555: The Oxford English Dictionary found that, based on a study of around 2.5 billion printed and online sources, "Internet" was capitalized in 54% of cases. The terms Internet and World Wide Web are often used interchangeably; it is common to speak of "going on the Internet" when using a web browser to view web pages . However, the World Wide Web , or the Web , is only one of a large number of Internet services,

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5082-489: The .NET Framework , and the DOM traversal API (NodeIterator and TreeWalker). Internet The Internet (or internet ) is the global system of interconnected computer networks that uses the Internet protocol suite (TCP/IP) to communicate between networks and devices. It is a network of networks that consists of private , public, academic, business, and government networks of local to global scope, linked by

5203-1050: The American Registry for Internet Numbers (ARIN) for North America , the Asia–Pacific Network Information Centre (APNIC) for Asia and the Pacific region , the Latin American and Caribbean Internet Addresses Registry (LACNIC) for Latin America and the Caribbean region, and the Réseaux IP Européens – Network Coordination Centre (RIPE NCC) for Europe , the Middle East , and Central Asia were delegated to assign IP address blocks and other Internet parameters to local registries, such as Internet service providers , from

5324-984: The Computer Science Network (CSNET). In 1982, the Internet Protocol Suite (TCP/IP) was standardized, which facilitated worldwide proliferation of interconnected networks. TCP/IP network access expanded again in 1986 when the National Science Foundation Network (NSFNet) provided access to supercomputer sites in the United States for researchers, first at speeds of 56 kbit/s and later at 1.5 Mbit/s and 45 Mbit/s. The NSFNet expanded into academic and research organizations in Europe, Australia, New Zealand and Japan in 1988–89. Although other network protocols such as UUCP and PTT public data networks had global reach well before this time, this marked

5445-544: The HyperText Markup Language (HTML), the first Web browser (which was also an HTML editor and could access Usenet newsgroups and FTP files), the first HTTP server software (later known as CERN httpd ), the first web server , and the first Web pages that described the project itself. In 1991 the Commercial Internet eXchange was founded, allowing PSInet to communicate with the other commercial networks CERFnet and Alternet. Stanford Federal Credit Union

5566-495: The International Network Working Group and commercial initiatives led to the development of various protocols and standards by which multiple separate networks could become a single network or "a network of networks". In 1974, Vint Cerf at Stanford University and Bob Kahn at DARPA published a proposal for "A Protocol for Packet Network Intercommunication". They used the term internet as

5687-485: The Merit Network and CYCLADES , were developed in the late 1960s and early 1970s. Early international collaborations for the ARPANET were rare. Connections were made in 1973 to Norway ( NORSAR and NDRE ), and to Peter Kirstein's research group at University College London (UCL), which provided a gateway to British academic networks , forming the first internetwork for resource sharing . ARPA projects,

5808-539: The United States and in the United Kingdom and France . The ARPANET initially served as a backbone for the interconnection of regional academic and military networks in the United States to enable resource sharing . The funding of the National Science Foundation Network as a new backbone in the 1980s, as well as private funding for other commercial extensions, encouraged worldwide participation in

5929-506: The Unix info format and Python 's splitlines string method. The names of some codes were changed in ISO 6429:1992 (or ECMA-48:1991) to be neutral with respect to writing direction. The abbreviations used were not changed, as the standard had already specified that those would remain unchanged when the standard is translated to other languages. In this table both new and old names are shown for

6050-460: The encoding of the Unicode characters that make up the document, and for expressing characters that, for one reason or another, cannot be used directly. Unicode code points in the following ranges are valid in XML 1.0 documents: XML 1.1 extends the set of allowed characters to include all the above, plus the remaining characters in the range U+0001–U+001F. At the same time, however, it restricts

6171-410: The infoset augmentation facility and attribute defaults. RELAX NG and Schematron intentionally do not provide these. A cluster of specifications closely related to XML have been developed, starting soon after the initial publication of XML 1.0. It is frequently the case that the term "XML" is used to refer to XML together with one or more of these other technologies that have come to be seen as part of

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6292-436: The "Format effector " (FE n ) characters BS, TAB, LF, VT, FF, and CR. Others are unused or have acquired different meanings such as NUL being the C string terminator . Some data transfer protocols such as ANPA-1312 , Kermit , and XMODEM do make extensive use of SOH, STX, ETX, EOT, ACK, NAK and SYN for purposes approximating their original definitions; and some file formats use the "Information Separators" (IS n ) such as

6413-430: The 8-bit forms of these codes were almost never used. CSI , DCS and OSC are used to control text terminals and terminal emulators , but almost always by using their 7-bit escape code representations. Nowadays if these codes are encountered it is far more likely they are intended to be printing characters from that position of Windows-1252 or Mac OS Roman . Except for NEL Unicode does not provide

6534-577: The C0 and C1 sets. The standard C0 control character set shown above is chosen with the sequence ESC ! @ and the above C1 set chosen with the sequence ESC " C . Several official and unofficial alternatives have been defined, but this is pretty much obsolete. Most were forced to retain a good deal of compatibility with the ASCII controls for interoperability. The standard makes ESC, SP and DEL "fixed" coded characters, which are available in their ASCII locations in all encodings that conform to

6655-507: The C0 format controls HT, LF, VT, FF, and CR (note BS is missing); the C0 information separators FS, GS, RS, US (and SP); and the C1 control NEL. The rest of the codes are transparent to Unicode and their meanings are left to higher-level protocols, with ISO/IEC 6429 suggested as a default. Unicode includes many additional format effector characters besides these, such as marks, embeds, isolates and pops for explicit bidirectional formatting, and

6776-579: The Internet and the depletion of available IPv4 addresses , a new version of IP IPv6 , was developed in the mid-1990s, which provides vastly larger addressing capabilities and more efficient routing of Internet traffic. IPv6 uses 128 bits for the IP address and was standardized in 1998. IPv6 deployment has been ongoing since the mid-2000s and is currently in growing deployment around the world, since Internet address registries ( RIRs ) began to urge all resource managers to plan rapid adoption and conversion. IPv6

6897-685: The Internet are contained in specially designated RFCs that constitute the Internet Standards . Other less rigorous documents are simply informative, experimental, or historical, or document the best current practices (BCP) when implementing Internet technologies. The Internet carries many applications and services , most prominently the World Wide Web, including social media , electronic mail , mobile applications , multiplayer online games , Internet telephony , file sharing , and streaming media services. Most servers that provide these services are today hosted in data centers , and content

7018-444: The Internet can then be accessed from places such as a park bench. Experiments have also been conducted with proprietary mobile wireless networks like Ricochet , various high-speed data services over cellular networks, and fixed wireless services. Modern smartphones can also access the Internet through the cellular carrier network. For Web browsing, these devices provide applications such as Google Chrome , Safari , and Firefox and

7139-618: The Internet for the benefit of all people throughout the world" . Its members include individuals (anyone may join) as well as corporations, organizations , governments, and universities. Among other activities ISOC provides an administrative home for a number of less formally organized groups that are involved in developing and managing the Internet, including: the IETF, Internet Architecture Board (IAB), Internet Engineering Steering Group (IESG), Internet Research Task Force (IRTF), and Internet Research Steering Group (IRSG). On 16 November 2005,

7260-444: The Internet model is the Internet Protocol (IP). IP enables internetworking and, in essence, establishes the Internet itself. Two versions of the Internet Protocol exist, IPv4 and IPv6 . For locating individual computers on the network, the Internet provides IP addresses . IP addresses are used by the Internet infrastructure to direct internet packets to their destinations. They consist of fixed-length numbers, which are found within

7381-514: The Internet via local computer networks. Hotspots providing such access include Wi-Fi cafés, where users need to bring their own wireless devices, such as a laptop or PDA . These services may be free to all, free to customers only, or fee-based. Grassroots efforts have led to wireless community networks . Commercial Wi-Fi services that cover large areas are available in many cities, such as New York , London , Vienna , Toronto , San Francisco , Philadelphia , Chicago and Pittsburgh , where

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7502-711: The Internet was included on USA Today ' s list of the New Seven Wonders . The word internetted was used as early as 1849, meaning interconnected or interwoven . The word Internet was used in 1945 by the United States War Department in a radio operator's manual, and in 1974 as the shorthand form of Internetwork. Today, the term Internet most commonly refers to the global system of interconnected computer networks , though it may also refer to any group of smaller networks. When it came into common use, most publications treated

7623-451: The Internet when needed to perform a function or obtain information, represent the bottom of the routing hierarchy. At the top of the routing hierarchy are the tier 1 networks , large telecommunication companies that exchange traffic directly with each other via very high speed fiber-optic cables and governed by peering agreements. Tier 2 and lower-level networks buy Internet transit from other providers to reach at least some parties on

7744-711: The Internet, the Internet Protocol address (IP address) space and the Domain Name System (DNS), are directed by a maintainer organization, the Internet Corporation for Assigned Names and Numbers (ICANN). The technical underpinning and standardization of the core protocols is an activity of the Internet Engineering Task Force (IETF), a non-profit organization of loosely affiliated international participants that anyone may associate with by contributing technical expertise. In November 2006,

7865-471: The NSFNET and Europe was installed between Cornell University and CERN , allowing much more robust communications than were capable with satellites. Later in 1990, Tim Berners-Lee began writing WorldWideWeb , the first web browser , after two years of lobbying CERN management. By Christmas 1990, Berners-Lee had built all the tools necessary for a working Web: the HyperText Transfer Protocol (HTTP) 0.9,

7986-507: The Pacific and in Africa. The number of unique mobile cellular subscriptions increased from 3.9 billion in 2012 to 4.8 billion in 2016, two-thirds of the world's population, with more than half of subscriptions located in Asia and the Pacific. The number of subscriptions was predicted to rise to 5.7 billion users in 2020. As of 2018 , 80% of the world's population were covered by

8107-861: The UK's national research and education network , JANET . Common methods of Internet access by users include dial-up with a computer modem via telephone circuits, broadband over coaxial cable , fiber optics or copper wires, Wi-Fi , satellite , and cellular telephone technology (e.g. 3G , 4G ). The Internet may often be accessed from computers in libraries and Internet cafés . Internet access points exist in many public places such as airport halls and coffee shops. Various terms are used, such as public Internet kiosk , public access terminal , and Web payphone . Many hotels also have public terminals that are usually fee-based. These terminals are widely accessed for various usages, such as ticket booking, bank deposit, or online payment . Wi-Fi provides wireless access to

8228-492: The Unicode character set. XML allows the use of any of the Unicode-defined encodings and any other encodings whose characters also appear in Unicode. XML also provides a mechanism whereby an XML processor can reliably, without any prior knowledge, determine which encoding is being used. Encodings other than UTF-8 and UTF-16 are not necessarily recognized by every XML parser (and in some cases not even UTF-16, even though

8349-826: The United Nations-sponsored World Summit on the Information Society in Tunis established the Internet Governance Forum (IGF) to discuss Internet-related issues. The communications infrastructure of the Internet consists of its hardware components and a system of software layers that control various aspects of the architecture. As with any computer network, the Internet physically consists of routers , media (such as cabling and radio links), repeaters, modems etc. However, as an example of internetworking , many of

8470-672: The United States Department of Defense (DoD). Research into packet switching , one of the fundamental Internet technologies, started in the work of Paul Baran at RAND in the early 1960s and, independently, Donald Davies at the United Kingdom's National Physical Laboratory (NPL) in 1965. After the Symposium on Operating Systems Principles in 1967, packet switching from the proposed NPL network and routing concepts proposed by Baran were incorporated into

8591-461: The United States surpassed those of cable television and nearly exceeded those of broadcast television . Many common online advertising practices are controversial and increasingly subject to regulation. When the Web developed in the 1990s, a typical web page was stored in completed form on a web server, formatted in HTML , ready for transmission to a web browser in response to a request. Over time,

8712-428: The XML core. Some other specifications conceived as part of the "XML Core" have failed to find wide adoption, including XInclude , XLink , and XPointer . The design goals of XML include, "It shall be easy to write programs which process XML documents." Despite this, the XML specification contains almost no information about how programmers might go about doing such processing. The XML Infoset specification provides

8833-405: The XML declaration. Comments begin with <!-- and end with --> . For compatibility with SGML , the string "--" (double-hyphen) is not allowed inside comments; this means comments cannot be nested. The ampersand has no special significance within comments, so entity and character references are not recognized as such, and there is no way to represent characters outside the character set of

8954-506: The XML processor inserts in the DTD itself and in the XML document wherever they are referenced, like character escapes. DTD technology is still used in many applications because of its ubiquity. A newer schema language, described by the W3C as the successor of DTDs, is XML Schema , often referred to by the initialism for XML Schema instances, XSD (XML Schema Definition). XSDs are far more powerful than DTDs in describing XML languages. They use

9075-434: The allowable parent/child relationships. The oldest schema language for XML is the document type definition (DTD), inherited from SGML. DTDs have the following benefits: DTDs have the following limitations: Two peculiar features that distinguish DTDs from other schema types are the syntactic support for embedding a DTD within XML documents and for defining entities , which are arbitrary fragments of text or markup that

9196-418: The architectural design of the Internet software systems has been assumed by the Internet Engineering Task Force (IETF). The IETF conducts standard-setting work groups, open to any individual, about the various aspects of Internet architecture. The resulting contributions and standards are published as Request for Comments (RFC) documents on the IETF web site. The principal methods of networking that enable

9317-412: The beginning of the Internet as an intercontinental network. Commercial Internet service providers (ISPs) emerged in 1989 in the United States and Australia. The ARPANET was decommissioned in 1990. Steady advances in semiconductor technology and optical networking created new economic opportunities for commercial involvement in the expansion of the network in its core and for delivering services to

9438-456: The bottom of the architecture is the link layer , which connects nodes on the same physical link, and contains protocols that do not require routers for traversal to other links. The protocol suite does not explicitly specify hardware methods to transfer bits, or protocols to manage such hardware, but assumes that appropriate technology is available. Examples of that technology include Wi-Fi , Ethernet , and DSL . The most prominent component of

9559-427: The canonical schema.) An XML document that adheres to basic XML rules is "well-formed"; one that adheres to its schema is "valid." IETF RFC 7303 (which supersedes the older RFC 3023 ), provides rules for the construction of media types for use in XML message. It defines three media types: application/xml ( text/xml is an alias), application/xml-external-parsed-entity ( text/xml-external-parsed-entity

9680-455: The complex array of physical connections that make up its infrastructure, the Internet is facilitated by bi- or multi-lateral commercial contracts, e.g., peering agreements , and by technical specifications or protocols that describe the exchange of data over the network. Indeed, the Internet is defined by its interconnections and routing policies. A subnetwork or subnet is a logical subdivision of an IP network . The practice of dividing

9801-414: The definition of XML-based languages, while programmers have developed many application programming interfaces (APIs) to aid the processing of XML data. The main purpose of XML is serialization , i.e. storing, transmitting, and reconstructing arbitrary data. For two disparate systems to exchange information, they need to agree upon a file format. XML standardizes this process. It is therefore analogous to

9922-613: The design of the ARPANET , an experimental resource sharing network proposed by ARPA. ARPANET development began with two network nodes which were interconnected between the University of California, Los Angeles (UCLA) and the Stanford Research Institute (now SRI International) on 29 October 1969. The third site was at the University of California, Santa Barbara , followed by the University of Utah . In

10043-528: The development of packet switching in the 1960s and the design of computer networks for data communication . The set of rules ( communication protocols ) to enable internetworking on the Internet arose from research and development commissioned in the 1970s by the Defense Advanced Research Projects Agency (DARPA) of the United States Department of Defense in collaboration with universities and researchers across

10164-434: The development of new networking technologies and the merger of many networks using DARPA's Internet protocol suite . The linking of commercial networks and enterprises by the early 1990s, as well as the advent of the World Wide Web , marked the beginning of the transition to the modern Internet, and generated sustained exponential growth as generations of institutional, personal , and mobile computers were connected to

10285-426: The document encoding. An example of a valid comment: <!--no need to escape <code> & such in comments--> XML 1.0 (Fifth Edition) and XML 1.1 support the direct use of almost any Unicode character in element names, attributes, comments, character data, and processing instructions (other than the ones that have special symbolic meaning in XML itself, such as the less-than sign, "<"). The following

10406-594: The documents and resources that they can provide. HyperText Transfer Protocol (HTTP) is the main access protocol of the World Wide Web. Web services also use HTTP for communication between software systems for information transfer, sharing and exchanging business data and logistics and is one of many languages or protocols that can be used for communication on the Internet. World Wide Web browser software, such as Microsoft 's Internet Explorer / Edge , Mozilla Firefox , Opera , Apple 's Safari , and Google Chrome , enable users to navigate from one web page to another via

10527-485: The first address of a network, followed by a slash character ( / ), and ending with the bit-length of the prefix. For example, 198.51.100.0 / 24 is the prefix of the Internet Protocol version 4 network starting at the given address, having 24 bits allocated for the network prefix, and the remaining 8 bits reserved for host addressing. Addresses in the range 198.51.100.0 to 198.51.100.255 belong to this network. The IPv6 address specification 2001:db8:: / 32

10648-429: The forwarding host (router) to other networks when no other route specification matches the destination IP address of a packet. While the hardware components in the Internet infrastructure can often be used to support other software systems, it is the design and the standardization process of the software that characterizes the Internet and provides the foundation for its scalability and success. The responsibility for

10769-707: The functions performing the parsing, or passed down (as function parameters) into lower-level functions, or returned (as function return values) to higher-level functions. Examples of pull parsers include Data::Edit::Xml in Perl , StAX in the Java programming language, XMLPullParser in Smalltalk , XMLReader in PHP , ElementTree.iterparse in Python , SmartXML in Red , System.Xml.XmlReader in

10890-603: The global Internet, though they may also engage in peering. An ISP may use a single upstream provider for connectivity, or implement multihoming to achieve redundancy and load balancing. Internet exchange points are major traffic exchanges with physical connections to multiple ISPs. Large organizations, such as academic institutions, large enterprises, and governments, may perform the same function as ISPs, engaging in peering and purchasing transit on behalf of their internal networks. Research networks tend to interconnect with large subnetworks such as GEANT , GLORIAD , Internet2 , and

11011-661: The hope that visitors will be impressed by the expert knowledge and free information and be attracted to the corporation as a result. Advertising on popular web pages can be lucrative, and e-commerce , which is the sale of products and services directly via the Web, continues to grow. Online advertising is a form of marketing and advertising which uses the Internet to deliver promotional marketing messages to consumers. It includes email marketing, search engine marketing (SEM), social media marketing, many types of display advertising (including web banner advertising), and mobile advertising . In 2011, Internet advertising revenues in

11132-505: The hyperlinks embedded in the documents. These documents may also contain any combination of computer data , including graphics, sounds, text , video , multimedia and interactive content that runs while the user is interacting with the page. Client-side software can include animations, games , office applications and scientific demonstrations. Through keyword -driven Internet research using search engines like Yahoo! , Bing and Google , users worldwide have easy, instant access to

11253-647: The interchange of data over the Internet. Hundreds of document formats using XML syntax have been developed, including RSS , Atom , Office Open XML , OpenDocument , SVG , COLLADA , and XHTML . XML also provides the base language for communication protocols such as SOAP and XMPP . It is one of the message exchange formats used in the Asynchronous JavaScript and XML (AJAX) programming technique. Many industry data standards, such as Health Level 7 , OpenTravel Alliance , FpML , MISMO , and National Information Exchange Model are based on XML and

11374-485: The late 1990s, it was estimated that traffic on the public Internet grew by 100 percent per year, while the mean annual growth in the number of Internet users was thought to be between 20% and 50%. This growth is often attributed to the lack of central administration, which allows organic growth of the network, as well as the non-proprietary nature of the Internet protocols, which encourages vendor interoperability and prevents any one company from exerting too much control over

11495-462: The network nodes are not necessarily Internet equipment per se. The internet packets are carried by other full-fledged networking protocols with the Internet acting as a homogeneous networking standard, running across heterogeneous hardware, with the packets guided to their destinations by IP routers. Internet service providers (ISPs) establish the worldwide connectivity between individual networks at various levels of scope. End-users who only access

11616-412: The network. As of 31 March 2011 , the estimated total number of Internet users was 2.095 billion (30% of world population ). It is estimated that in 1993 the Internet carried only 1% of the information flowing through two-way telecommunication . By 2000 this figure had grown to 51%, and by 2007 more than 97% of all telecommunicated information was carried over the Internet. The Internet

11737-1058: The network. Although the Internet was widely used by academia in the 1980s, the subsequent commercialization in the 1990s and beyond incorporated its services and technologies into virtually every aspect of modern life. Most traditional communication media, including telephone , radio , television , paper mail, and newspapers, are reshaped, redefined, or even bypassed by the Internet, giving birth to new services such as email , Internet telephone , Internet television , online music , digital newspapers, and video streaming websites. Newspapers, books, and other print publishing have adapted to website technology or have been reshaped into blogging , web feeds , and online news aggregators . The Internet has enabled and accelerated new forms of personal interaction through instant messaging , Internet forums , and social networking services . Online shopping has grown exponentially for major retailers, small businesses , and entrepreneurs , as it enables firms to extend their " brick and mortar " presence to serve

11858-414: The networking technologies that interconnect networks at their borders and exchange traffic across them. The Internet layer implements the Internet Protocol (IP) which enables computers to identify and locate each other by IP address and route their traffic via intermediate (transit) networks. The Internet Protocol layer code is independent of the type of network that it is physically running over. At

11979-481: The packet. IP addresses are generally assigned to equipment either automatically via DHCP , or are configured. However, the network also supports other addressing systems. Users generally enter domain names (e.g. "en.wikipedia.org") instead of IP addresses because they are easier to remember; they are converted by the Domain Name System (DNS) into IP addresses which are more efficient for routing purposes. Internet Protocol version 4 (IPv4) defines an IP address as

12100-435: The principal name spaces of the Internet are administered by the Internet Corporation for Assigned Names and Numbers (ICANN). ICANN is governed by an international board of directors drawn from across the Internet technical, business, academic, and other non-commercial communities. ICANN coordinates the assignment of unique identifiers for use on the Internet, including domain names , IP addresses, application port numbers in

12221-586: The process of creating and serving web pages has become dynamic, creating a flexible design, layout, and content. Websites are often created using content management software with, initially, very little content. Contributors to these systems, who may be paid staff, members of an organization or the public, fill underlying databases with content using editing pages designed for that purpose while casual visitors view and read this content in HTML form. There may or may not be editorial, approval and security systems built into

12342-685: The process of taking newly entered content and making it available to the target visitors. Email is an important communications service available via the Internet. The concept of sending electronic text messages between parties, analogous to mailing letters or memos, predates the creation of the Internet. Pictures, documents, and other files are sent as email attachments . Email messages can be cc-ed to multiple email addresses . C0 and C1 control codes The C0 and C1 control code or control character sets define control codes for use in text by computer systems that use ASCII and derivatives of ASCII. The codes represent additional information about

12463-442: The public. In mid-1989, MCI Mail and Compuserve established connections to the Internet, delivering email and public access products to the half million users of the Internet. Just months later, on 1 January 1990, PSInet launched an alternate Internet backbone for commercial use; one of the networks that added to the core of the commercial Internet of later years. In March 1990, the first high-speed T1 (1.5 Mbit/s) link between

12584-469: The region had a handful of plans to choose from (across all mobile network operators) while others, such as Colombia , offered as many as 30 pre-paid and 34 post-paid plans. A study of eight countries in the Global South found that zero-rated data plans exist in every country, although there is a great range in the frequency with which they are offered and actually used in each. The study looked at

12705-437: The renamed controls (the old name is the one matching the abbreviation). Unicode provides Control Pictures that can replace C0 control characters to make them visible on screen. However caret notation is used more often. Teletype used these for the paper tape reader and the paper tape punch. The first use became the de facto standard for software flow control . In 1973, ECMA-35 and ISO 2022 attempted to define

12826-559: The rich features of the XML schema specification. In publishing, Darwin Information Typing Architecture is an XML industry data standard. XML is used extensively to underpin various publishing formats. One of the applications of XML is in the transfer of Operational meteorology (OPMET) information based on IWXXM standards. The material in this section is based on the XML Specification . This

12947-590: The rise of near-instant communication by email, instant messaging , telephony ( Voice over Internet Protocol or VoIP), two-way interactive video calls , and the World Wide Web with its discussion forums , blogs, social networking services , and online shopping sites. Increasing amounts of data are transmitted at higher and higher speeds over fiber optic networks operating at 1 Gbit/s, 10 Gbit/s, or more. The Internet continues to grow, driven by ever-greater amounts of online information and knowledge, commerce, entertainment and social networking services. During

13068-635: The standard mandates it to also be recognized). XML provides escape facilities for including characters that are problematic to include directly. For example: There are five predefined entities : All permitted Unicode characters may be represented with a numeric character reference . Consider the Chinese character "中", whose numeric code in Unicode is hexadecimal 4E2D, or decimal 20,013. A user whose keyboard offers no method for entering this character could still insert it in an XML document encoded either as &#20013; or &#x4e2d; . Similarly,

13189-443: The standard. It also specifies that if a C0 set included transmission control (TC n ) codes, they must be encoded at their ASCII locations and could not be put in a C1 set, and any new transmission controls must be in a C1 set. Unicode reserves the 65 code points described above for compatibility with the C0 and C1 control codes, giving them the general category Cc (control). These are: Unicode only specifies semantics for

13310-457: The string "I <3 Jörg" could be encoded for inclusion in an XML document as I &lt;3 J&#xF6;rg . &#0; is not permitted because the null character is one of the control characters excluded from XML, even when using a numeric character reference. An alternative encoding mechanism such as Base64 is needed to represent such characters. Comments may appear anywhere in a document outside other markup. Comments cannot appear before

13431-452: The subnet mask for the prefix 198.51.100.0 / 24 . Traffic is exchanged between subnetworks through routers when the routing prefixes of the source address and the destination address differ. A router serves as a logical or physical boundary between the subnets. The benefits of subnetting an existing network vary with each deployment scenario. In the address allocation architecture of the Internet using CIDR and in large organizations, it

13552-697: The text, such as the position of a cursor, an instruction to start a new line, or a message that the text has been received. C0 codes are the range 00 HEX –1F HEX and the default C0 set was originally defined in ISO 646 ( ASCII ). C1 codes are the range 80 HEX –9F HEX and the default C1 set was originally defined in ECMA-48 (harmonized later with ISO 6429). The ISO/IEC 2022 system of specifying control and graphic characters allows other C0 and C1 sets to be available for specialized applications, but they are rarely used. ASCII defined 32 control characters, plus

13673-462: The top three to five carriers by market share in Bangladesh, Colombia, Ghana, India, Kenya, Nigeria, Peru and Philippines. Across the 181 plans examined, 13 percent were offering zero-rated services. Another study, covering Ghana , Kenya , Nigeria and South Africa , found Facebook 's Free Basics and Misplaced Pages Zero to be the most commonly zero-rated content. The Internet standards describe

13794-405: The transport protocols, and many other parameters. Globally unified name spaces are essential for maintaining the global reach of the Internet. This role of ICANN distinguishes it as perhaps the only central coordinating body for the global Internet. Regional Internet registries (RIRs) were established for five regions of the world. The African Network Information Center (AfriNIC) for Africa ,

13915-446: The use of C0 and C1 control characters other than U+0009 (Horizontal Tab), U+000A (Line Feed), U+000D (Carriage Return), and U+0085 (Next Line) by requiring them to be written in escaped form (for example U+0001 must be written as &#x01; or its equivalent). In the case of C1 characters, this restriction is a backwards incompatibility; it was introduced to allow common encoding errors to be detected. The code point U+0000 (Null)

14036-472: The use of much more memory, but are often found more convenient for use by programmers; some include declarative retrieval of document components via the use of XPath expressions. XSLT is designed for declarative description of XML document transformations, and has been widely implemented both in server-side packages and Web browsers. XQuery overlaps XSLT in its functionality, but is designed more for searching of large XML databases . Simple API for XML (SAX)

14157-426: The vendor support of XML Schemas yet, and are to some extent a grassroots reaction of industrial publishers to the lack of utility of XML Schemas for publishing . Some schema languages not only describe the structure of a particular XML format but also offer limited facilities to influence processing of individual XML files that conform to this format. DTDs and XSDs both have this ability; they can for instance provide

14278-455: The volume of Internet traffic started experiencing similar characteristics as that of the scaling of MOS transistors , exemplified by Moore's law , doubling every 18 months. This growth, formalized as Edholm's law , was catalyzed by advances in MOS technology , laser light wave systems, and noise performance. Since 1995, the Internet has tremendously impacted culture and commerce, including

14399-533: The word Internet as a capitalized proper noun ; this has become less common. This reflects the tendency in English to capitalize new terms and move them to lowercase as they become familiar. The word is sometimes still capitalized to distinguish the global internet from smaller networks, though many publications, including the AP Stylebook since 2016, recommend the lowercase form in every case. In 2016,

14520-715: Was DIN 31626 , a specialised set for bibliographic use which was registered in 1979. The more common general-use ISO/IEC 6429 set was registered in 1983, although the ECMA-48 specification upon which it was based had been first published in 1976 and JIS X 0211 (formerly JIS C 6323). Symbolic names defined by RFC   1345 and early drafts of ISO 10646, but not in ISO/IEC 6429 ( PAD , HOP and SGC ) are also used. Except for SS2 and SS3 in EUC-JP text, and NEL in text transcoded from EBCDIC ,

14641-558: Was the first financial institution to offer online Internet banking services to all of its members in October 1994. In 1996, OP Financial Group , also a cooperative bank , became the second online bank in the world and the first in Europe. By 1995, the Internet was fully commercialized in the U.S. when the NSFNet was decommissioned, removing the last restrictions on use of the Internet to carry commercial traffic. As technology advanced and commercial opportunities fueled reciprocal growth,

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