In computer networks , download means to receive data from a remote system, typically a server such as a web server , an FTP server, an email server, or other similar systems. This contrasts with uploading, where data is sent to a remote server.
100-470: A download is a file offered for downloading or that has been downloaded, or the process of receiving such a file. Downloading generally transfers entire files for local storage and later use, as contrasted with streaming , where the data is used nearly immediately while the transmission is still in progress and may not be stored long-term. Websites that offer streaming media or media displayed in-browser, such as YouTube , increasingly place restrictions on
200-707: A file of punched cards ." In February 1950, in a Radio Corporation of America (RCA) advertisement in Popular Science magazine describing a new "memory" vacuum tube it had developed, RCA stated: "the results of countless computations can be kept 'on file' and taken out again. Such a 'file' now exists in a 'memory' tube developed at RCA Laboratories. Electronically it retains figures fed into calculating machines, holds them in storage while it memorizes new ones – speeds intelligent solutions through mazes of mathematics." In 1952, "file" denoted, among other things, information stored on punched cards . In early use,
300-510: A computer file is a resource for recording data on a computer storage device , primarily identified by its filename . Just as words can be written on paper, so too can data be written to a computer file. Files can be shared with and transferred between computers and mobile devices via removable media , networks , or the Internet . Different types of computer files are designed for different purposes. A file may be designed to store
400-462: A hard disk . Hard disks have been the ubiquitous form of non-volatile storage since the early 1960s. Where files contain only temporary information, they may be stored in RAM . Computer files can be also stored on other media in some cases, such as magnetic tapes , compact discs , Digital Versatile Discs , Zip drives , USB flash drives , etc. The use of solid state drives is also beginning to rival
500-428: A link to the file. There can be many links to a file, but when they are all removed, the kernel considers that file's memory space free to be reallocated. This free space is commonly considered a security risk (due to the existence of file recovery software ). Any secure-deletion program uses kernel-space (system) functions to wipe the file's data. File moves within a file system complete almost immediately because
600-454: A FAT extension allowing long file names). File manager programs are utility programs that allow users to manipulate files directly. They allow you to move, create, delete and rename files and folders, although they do not actually allow you to read the contents of a file or store information in it. Every computer system provides at least one file-manager program for its native file system. For example, File Explorer (formerly Windows Explorer)
700-491: A broad array of electronic, wireless, and optical networking technologies. The Internet carries an extensive range of information resources and services, such as the inter-linked hypertext documents of the World Wide Web and the infrastructure to support email. Computer programming is the process of writing, testing, debugging, and maintaining the source code and documentation of computer programs. This source code
800-489: A central server, which incurs bandwidth and hard disk space costs due to the files generated with each download. Anonymous and open hosting servers make it difficult to hold hosts accountable. Taking legal action against the technologies behind unauthorized "file sharing" has proven successful for centralized networks like Napster , and untenable for decentralized networks like Gnutella or BitTorrent . The leading YouTube audio-ripping site agreed to shut down after being sued by
900-497: A computer's capabilities, but typically do not directly apply them in the performance of tasks that benefit the user, unlike application software. Application software, also known as an application or an app , is computer software designed to help the user perform specific tasks. Examples include enterprise software , accounting software , office suites , graphics software , and media players . Many application programs deal principally with documents . Apps may be bundled with
1000-427: A device, no space will have been freed up on the source device or partition. The user would need to merge the remaining files from the source, including the incompletely written (truncated) last file. With the individual deletion method, the file moving software also does not need to cumulatively keep track of all files finished transferring for the case that a user manually aborts the file transfer. A file manager using
1100-524: A directory and a file. In environments in which a file is named, a file's name and the path to the file's directory must uniquely identify it among all other files in the computer system—no two files can have the same name and path. Where a file is anonymous, named references to it will exist within a namespace. In most cases, any name within the namespace will refer to exactly zero or one file. However, any file may be represented within any namespace by zero, one or more names. Any string of characters may be
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#17327725048351200-847: A dot (period) at the end of a file name, followed by a few letters to identify the type of file. An extension of .txt identifies a text file; a .doc extension identifies any type of document or documentation, commonly in the Microsoft Word file format ; and so on . Even when extensions are used in a computer system, the degree to which the computer system recognizes and heeds them can vary; in some systems, they are required, while in other systems, they are completely ignored if they are presented. Many modern computer systems provide methods for protecting files against accidental and deliberate damage. Computers that allow for multiple users implement file permissions to control who may or may not modify, delete, or create files and folders. For example,
1300-660: A file. Downloading is not the same as data transfer ; moving or copying data between two storage devices would be data transfer , but receiving data from the Internet or BBS is downloading . Downloading media files involves the use of linking and framing Internet material and relates to copyright law. Streaming and downloading can involve making copies of works that infringe on copyrights or other rights, and organizations running such websites may become vicariously liable for copyright infringement by causing others to do so. Open hosting servers allow people to upload files to
1400-514: A given user may be granted only permission to read a file or folder, but not to modify or delete it; or a user may be given permission to read and modify files or folders, but not to execute them. Permissions may also be used to allow only certain users to see the contents of a file or folder. Permissions protect against unauthorized tampering or destruction of information in files, and keep private information confidential from unauthorized users. Another protection mechanism implemented in many computers
1500-533: A huge coalition of recording labels. Downloading and streaming relate to the more general usage of the Internet to facilitate copyright infringement , also known as "software piracy". As overt static hosting of unauthorized copies of works (i.e., centralized networks) is often quickly and uncontroversially rebuffed, legal issues have in recent years tended to deal with the usage of dynamic web technologies (decentralized networks, trackerless BitTorrents) to circumvent
1600-446: A later point through overwriting. There are many ways by which a file can become corrupted. Most commonly, the issue happens in the process of writing the file to a disk . For example, if an image-editing program unexpectedly crashes while saving an image, that file may be corrupted because the program could not save its entirety. The program itself might warn the user that there was an error, allowing for another attempt at saving
1700-420: A low level, on a file. Only the kernel deals with files, and it handles all user-space interaction with files in a manner that is transparent to the user-space programs. The operating system provides a level of abstraction , which means that interaction with a file from user-space is simply through its filename (instead of its inode ). For example, rm filename will not delete the file itself, but only
1800-406: A name of its own, but also a path, which identifies the folder or folders in which a file or folder resides. In the path, some sort of special character—such as a slash—is used to separate the file and folder names. For example, in the illustration shown in this article, the path /Payroll/Salaries/Managers uniquely identifies a file called Managers in a folder called Salaries , which in turn
1900-418: A number of bytes , that indicates how much storage is occupied by the file. In most modern operating systems the size can be any non-negative whole number of bytes up to a system limit. Many older operating systems kept track only of the number of blocks or tracks occupied by a file on a physical storage device. In such systems, software employed other methods to track the exact byte count (e.g., CP/M used
2000-443: A payroll file might contain information concerning all the employees in a company and their payroll details; each record in the payroll file concerns just one employee, and all the records have the common trait of being related to payroll—this is very similar to placing all payroll information into a specific filing cabinet in an office that does not have a computer. A text file may contain lines of text, corresponding to printed lines on
2100-429: A piece of paper. Alternatively, a file may contain an arbitrary binary image (a blob ) or it may contain an executable . The way information is grouped into a file is entirely up to how it is designed. This has led to a plethora of more or less standardized file structures for all imaginable purposes, from the simplest to the most complex. Most computer files are used by computer programs which create, modify or delete
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#17327725048352200-458: A set of instructions called a computer program . The program has an executable form that the computer can use directly to execute the instructions. The same program in its human-readable source code form, enables a programmer to study and develop a sequence of steps known as an algorithm . Because the instructions can be carried out in different types of computers, a single set of source instructions converts to machine instructions according to
2300-433: A special control character, Ctrl-Z , to signal the end of text files). The general definition of a file does not require that its size have any real meaning, however, unless the data within the file happens to correspond to data within a pool of persistent storage. A special case is a zero byte file ; these files can be newly created files that have not yet had any data written to them, or may serve as some kind of flag in
2400-435: A superposition, i.e. in both states of one and zero, simultaneously. Thus, the value of the qubit is not between 1 and 0, but changes depending on when it is measured. This trait of qubits is known as quantum entanglement , and is the core idea of quantum computing that allows quantum computers to do large scale computations. Quantum computing is often used for scientific research in cases where traditional computers do not have
2500-622: A technological process, as well as the conditions laid down in Article 5(5) of that directive, and that they may therefore be made without the authorisation of the copyright holders." On April 17, 2009, a Swedish court convicted four men operating The Pirate Bay Internet site of criminal copyright infringement. The Pirate Bay was established in 2003 by the Swedish anti-copyright organization Piratbyrån to provide information needed to download film or music files from third parties, many of whom copied
2600-438: A tree-like structure in which one "master folder" (or "root folder" — the name varies from one operating system to another) can contain any number of levels of other folders and files. Folders can be named just as files can (except for the root folder, which often does not have a name). The use of folders makes it easier to organize files in a logical way. When a computer allows the use of folders, each file and folder has not only
2700-419: A well-formed name for a file or a link depending upon the context of application. Whether or not a name is well-formed depends on the type of computer system being used. Early computers permitted only a few letters or digits in the name of a file, but modern computers allow long names (some up to 255 characters) containing almost any combination of Unicode letters or Unicode digits, making it easier to understand
2800-444: A written message, a document, a spreadsheet , an image , a video , a program , or any wide variety of other kinds of data. Certain files can store multiple data types at once. By using computer programs, a person can open, read, change, save, and close a computer file. Computer files may be reopened, modified, and copied an arbitrary number of times. Files are typically organized in a file system , which tracks file locations on
2900-421: Is spintronics . Spintronics can provide computing power and storage, without heat buildup. Some research is being done on hybrid chips, which combine photonics and spintronics. There is also research ongoing on combining plasmonics , photonics, and electronics. Cloud computing is a model that allows for the use of computing resources, such as servers or applications, without the need for interaction between
3000-460: Is a discipline that integrates several fields of electrical engineering and computer science required to develop computer hardware and software. Computer engineers usually have training in electronic engineering (or electrical engineering ), software design , and hardware-software integration, rather than just software engineering or electronic engineering. Computer engineers are involved in many hardware and software aspects of computing, from
3100-436: Is a read-only flag. When this flag is turned on for a file (which can be accomplished by a computer program or by a human user), the file can be examined, but it cannot be modified. This flag is useful for critical information that must not be modified or erased, such as special files that are used only by internal parts of the computer system. Some systems also include a hidden flag to make certain files invisible; this flag
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3200-414: Is a person who writes computer software. The term computer programmer can refer to a specialist in one area of computer programming or to a generalist who writes code for many kinds of software. One who practices or professes a formal approach to programming may also be known as a programmer analyst. A programmer's primary computer language ( C , C++ , Java , Lisp , Python , etc.) is often prefixed to
3300-409: Is also synonymous with counting and calculating . In earlier times, it was used in reference to the action performed by mechanical computing machines , and before that, to human computers . The history of computing is longer than the history of computing hardware and includes the history of methods intended for pen and paper (or for chalk and slate) with or without the aid of tables. Computing
3400-479: Is an area of memory which is manipulated to establish a filename etc. and then passed to the operating system as a parameter; it was used by older IBM operating systems and early PC operating systems including CP/M and early versions of MS-DOS . A file handle is generally either an opaque data type or an integer; it was introduced in around 1961 by the ALGOL-based Burroughs MCP running on
3500-414: Is an area of research that brings together the disciplines of computer science, information theory, and quantum physics. While the idea of information as part of physics is relatively new, there appears to be a strong tie between information theory and quantum mechanics. Whereas traditional computing operates on a binary system of ones and zeros, quantum computing uses qubits . Qubits are capable of being in
3600-741: Is commonly used in Microsoft Windows operating systems, and Nautilus is common under several distributions of Linux. Computing Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery . It includes the study and experimentation of algorithmic processes, and the development of both hardware and software. Computing has scientific, engineering, mathematical, technological, and social aspects. Major computing disciplines include computer engineering , computer science , cybersecurity , data science , information systems , information technology , and software engineering . The term computing
3700-423: Is computer software designed to operate and control computer hardware, and to provide a platform for running application software. System software includes operating systems , utility software , device drivers , window systems , and firmware . Frequently used development tools such as compilers , linkers , and debuggers are classified as system software. System software and middleware manage and integrate
3800-420: Is contained in a folder called Payroll . The folder and file names are separated by slashes in this example; the topmost or root folder has no name, and so the path begins with a slash (if the root folder had a name, it would precede this first slash). Many computer systems use extensions in file names to help identify what they contain, also known as the file type. On Windows computers, extensions consist of
3900-464: Is corrupted. There are services that provide on demand file corruption, which essentially fill a given file with random data so that it cannot be opened or read, yet still seems legitimate. One of the most effective countermeasures for unintentional file corruption is backing up important files. In the event of an important file becoming corrupted, the user can simply replace it with the backed up version. When computer files contain information that
4000-476: Is denoted CMOS-integrated nanophotonics (CINP). One benefit of optical interconnects is that motherboards, which formerly required a certain kind of system on a chip (SoC), can now move formerly dedicated memory and network controllers off the motherboards, spreading the controllers out onto the rack. This allows standardization of backplane interconnects and motherboards for multiple types of SoCs, which allows more timely upgrades of CPUs. Another field of research
4100-613: Is extremely important, a back-up process is used to protect against disasters that might destroy the files. Backing up files simply means making copies of the files in a separate location so that they can be restored if something happens to the computer, or if they are deleted accidentally. There are many ways to back up files. Most computer systems provide utility programs to assist in the back-up process, which can become very time-consuming if there are many files to safeguard. Files are often copied to removable media such as writable CDs or cartridge tapes. Copying files to another hard disk in
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4200-490: Is intimately tied to the representation of numbers, though mathematical concepts necessary for computing existed before numeral systems . The earliest known tool for use in computation is the abacus , and it is thought to have been invented in Babylon circa between 2700 and 2300 BC. Abaci, of a more modern design, are still used as calculation tools today. The first recorded proposal for using digital electronics in computing
4300-710: Is its potential to support energy efficiency. Allowing thousands of instances of computation to occur on one single machine instead of thousands of individual machines could help save energy. It could also ease the transition to renewable energy source, since it would suffice to power one server farm with renewable energy, rather than millions of homes and offices. However, this centralized computing model poses several challenges, especially in security and privacy. Current legislation does not sufficiently protect users from companies mishandling their data on company servers. This suggests potential for further legislative regulations on cloud computing and tech companies. Quantum computing
4400-559: Is sometimes considered a sub-discipline of electrical engineering , telecommunications, computer science , information technology, or computer engineering , since it relies upon the theoretical and practical application of these disciplines. The Internet is a global system of interconnected computer networks that use the standard Internet Protocol Suite (TCP/IP) to serve billions of users. This includes millions of private, public, academic, business, and government networks, ranging in scope from local to global. These networks are linked by
4500-687: Is the application of computers and telecommunications equipment to store, retrieve, transmit, and manipulate data, often in the context of a business or other enterprise. The term is commonly used as a synonym for computers and computer networks, but also encompasses other information distribution technologies such as television and telephones. Several industries are associated with information technology, including computer hardware, software, electronics , semiconductors , internet, telecom equipment , e-commerce , and computer services . DNA-based computing and quantum computing are areas of active research for both computing hardware and software, such as
4600-509: Is the study of complementary networks of hardware and software (see information technology) that people and organizations use to collect, filter, process, create, and distribute data . The ACM 's Computing Careers describes IS as: "A majority of IS [degree] programs are located in business schools; however, they may have different names such as management information systems, computer information systems, or business information systems. All IS degrees combine business and computing topics, but
4700-449: Is thus often developed by a team of domain experts, each a specialist in some area of development. However, the term programmer may apply to a range of program quality, from hacker to open source contributor to professional. It is also possible for a single programmer to do most or all of the computer programming needed to generate the proof of concept to launch a new killer application . A programmer, computer programmer, or coder
4800-435: Is used by the computer system to hide essential system files that users should not alter. Any file that has any useful purpose must have some physical manifestation. That is, a file (an abstract concept) in a real computer system must have a real physical analogue if it is to exist at all. In physical terms, most computer files are stored on some type of data storage device. For example, most operating systems store files on
4900-429: Is written in a programming language , which is an artificial language that is often more restrictive than natural languages , but easily translated by the computer. Programming is used to invoke some desired behavior (customization) from the machine. Writing high-quality source code requires knowledge of both the computer science domain and the domain in which the application will be used. The highest-quality software
5000-627: The mv command for instance, the former method is used when selecting files individually, possibly with the use of wildcards (example: mv -n sourcePath/* targetPath , while the latter method is used when selecting entire directories (example: mv -n sourcePath targetPath ). Microsoft Windows Explorer uses the former method for mass storage file moves, but the latter method using Media Transfer Protocol , as described in Media Transfer Protocol § File move behavior . The former method (individual deletion from source) has
5100-468: The Burroughs B5000 but is now ubiquitous. When a file is said to be corrupted, it is because its contents have been saved to the computer in such a way that they cannot be properly read, either by a human or by software. Depending on the extent of the damage, the original file can sometimes be recovered , or at least partially understood. A file may be created corrupt, or it may be corrupted at
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#17327725048355200-557: The CPU type. The execution process carries out the instructions in a computer program. Instructions express the computations performed by the computer. They trigger sequences of simple actions on the executing machine. Those actions produce effects according to the semantics of the instructions. Computer hardware includes the physical parts of a computer, including the central processing unit , memory , and input/output . Computational logic and computer architecture are key topics in
5300-619: The NTFS file system that is the normal file system for recent versions of Windows. Each system has its own advantages and disadvantages. Standard FAT allows only eight-character file names (plus a three-character extension) with no spaces, for example, whereas NTFS allows much longer names that can contain spaces. You can call a file " Payroll records " in NTFS, but in FAT you would be restricted to something like payroll.dat (unless you were using VFAT ,
5400-444: The function of the program it implements, either by directly providing instructions to the computer hardware or by serving as input to another piece of software. The term was coined to contrast with the old term hardware (meaning physical devices). In contrast to hardware, software is intangible. Software is also sometimes used in a more narrow sense, meaning application software only. System software, or systems software,
5500-660: The European Parliament and of the Council of 22 May 2001 on the harmonisation of certain aspects of copyright and related rights in the information society must be interpreted as meaning that the copies on the user's computer screen and the copies in the internet 'cache' of that computer's hard disk, made by an end-user in the course of viewing a website, satisfy the conditions that those copies must be temporary, that they must be transient or incidental in nature and that they must constitute an integral and essential part of
5600-598: The ability of copyright owners to directly engage particular distributors and consumers. In Europe, the Court of Justice of the European Union (CJEU) has ruled that it is legal to create temporary or cached copies of works (copyrighted or otherwise) online. The ruling relates to the British Meltwater case settled on 5 June 2014. The judgement of the court states that: "Article 5 of Directive 2001/29/EC of
5700-422: The ability of users to save these materials to their computers after they have been received. Downloading on computer networks involves retrieving data from a remote system, like a web server, FTP server, or email server, unlike uploading, where data is sent to a remote server. A download can refer to a file made available for retrieval or one that has been received, encompassing the entire process of obtaining such
5800-880: The above titles, and those who work in a web environment often prefix their titles with Web . The term programmer can be used to refer to a software developer , software engineer, computer scientist , or software analyst . However, members of these professions typically possess other software engineering skills, beyond programming. The computer industry is made up of businesses involved in developing computer software, designing computer hardware and computer networking infrastructures, manufacturing computer components, and providing information technology services, including system administration and maintenance. The software industry includes businesses engaged in development , maintenance , and publication of software. The industry also includes software services , such as training , documentation , and consulting. Computer engineering
5900-410: The archive file are to lower the number of files for easier transfer, to reduce storage usage, or just to organize outdated files. The archive file must often be unpacked before next using. The most basic operations that programs can perform on a file are: Files on a computer can be created, moved, modified, grown, shrunk ( truncated ), and deleted. In most cases, computer programs that are executed on
6000-407: The benefit that space is released from the source device or partition imminently after the transfer has begun, meaning after the first file is finished. With the latter method, space is only freed after the transfer of the entire selection has finished. If an incomplete file transfer with the latter method is aborted unexpectedly, perhaps due to an unexpected power-off, system halt or disconnection of
6100-457: The challenges in implementing computations. For example, programming language theory studies approaches to the description of computations, while the study of computer programming investigates the use of programming languages and complex systems . The field of human–computer interaction focuses on the challenges in making computers and computations useful, usable, and universally accessible to humans. The field of cybersecurity pertains to
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#17327725048356200-560: The computer and its system software, or may be published separately. Some users are satisfied with the bundled apps and need never install additional applications. The system software manages the hardware and serves the application, which in turn serves the user. Application software applies the power of a particular computing platform or system software to a particular purpose. Some apps, such as Microsoft Office , are developed in multiple versions for several different platforms; others have narrower requirements and are generally referred to by
6300-559: The computer handle these operations, but the user of a computer can also manipulate files if necessary. For instance, Microsoft Word files are normally created and modified by the Microsoft Word program in response to user commands, but the user can also move, rename , or delete these files directly by using a file manager program such as Windows Explorer (on Windows computers) or by command lines (CLI). In Unix-like systems, user space programs do not operate directly, at
6400-410: The data content does not need to be rewritten. Only the paths need to be changed. There are two distinct implementations of file moves. When moving files between devices or partitions, some file managing software deletes each selected file from the source directory individually after being transferred, while other software deletes all files at once only after every file has been transferred. With
6500-448: The design of individual microprocessors , personal computers, and supercomputers , to circuit design . This field of engineering includes not only the design of hardware within its own domain, but also the interactions between hardware and the context in which it operates. Software engineering is the application of a systematic, disciplined, and quantifiable approach to the design, development, operation, and maintenance of software, and
6600-414: The development of quantum algorithms . Potential infrastructure for future technologies includes DNA origami on photolithography and quantum antennae for transferring information between ion traps. By 2011, researchers had entangled 14 qubits . Fast digital circuits , including those based on Josephson junctions and rapid single flux quantum technology, are becoming more nearly realizable with
6700-437: The discovery of nanoscale superconductors . Fiber-optic and photonic (optical) devices, which already have been used to transport data over long distances, are starting to be used by data centers, along with CPU and semiconductor memory components. This allows the separation of RAM from CPU by optical interconnects. IBM has created an integrated circuit with both electronic and optical information processing in one chip. This
6800-706: The disk and enables user access. The word "file" derives from the Latin filum ("a thread, string"). "File" was used in the context of computer storage as early as January 1940. In Punched Card Methods in Scientific Computation , W. J. Eckert stated, "The first extensive use of the early Hollerith Tabulator in astronomy was made by Comrie . He used it for building a table from successive differences, and for adding large numbers of harmonic terms". "Tables of functions are constructed from their differences with great efficiency, either as printed tables or as
6900-440: The document file is arranged in a format that the word-processing program understands, the user is able to choose the name and location of the file and provide the bulk of the information (such as words and text) that will be stored in the file. Many applications pack all their data files into a single file called an archive file , using internal markers to discern the different types of information contained within. The benefits of
7000-686: The emphasis between technical and organizational issues varies among programs. For example, programs differ substantially in the amount of programming required." The study of IS bridges business and computer science , using the theoretical foundations of information and computation to study various business models and related algorithmic processes within a computer science discipline. The field of Computer Information Systems (CIS) studies computers and algorithmic processes, including their principles, their software and hardware designs, their applications, and their impact on society while IS emphasizes functionality over design. Information technology (IT)
7100-665: The engineering paradigm. The generally accepted concepts of Software Engineering as an engineering discipline have been specified in the Guide to the Software Engineering Body of Knowledge (SWEBOK). The SWEBOK has become an internationally accepted standard in ISO/IEC TR 19759:2015. Computer science or computing science (abbreviated CS or Comp Sci) is the scientific and practical approach to computation and its applications. A computer scientist specializes in
7200-403: The existence of directory hierarchies, i.e., directories containing sub-directories. A name that refers to a file within a directory must be typically unique. In other words, there must be no identical names within a directory. However, in some operating systems, a name may include a specification of type that means a directory can contain an identical name for more than one type of object such as
7300-434: The field of computer hardware. Computer software, or just software , is a collection of computer programs and related data, which provides instructions to a computer. Software refers to one or more computer programs and data held in the storage of the computer. It is a set of programs, procedures, algorithms, as well as its documentation concerned with the operation of a data processing system. Program software performs
7400-414: The file and the son is the current copy. The way a computer organizes, names, stores and manipulates files is globally referred to as its file system . Most computers have at least one file system. Some computers allow the use of several different file systems. For instance, on newer MS Windows computers, the older FAT-type file systems of MS-DOS and old versions of Windows are supported, in addition to
7500-414: The file system) file-specific data outside of the file format, but linked to the file, for example extended attributes or forks . On other file systems this can be done via sidecar files or software-specific databases. All those methods, however, are more susceptible to loss of metadata than container and archive file formats. At any instant in time, a file has a specific size, normally expressed as
7600-526: The file system, or are accidents (the results of aborted disk operations). For example, the file to which the link /bin/ls points in a typical Unix-like system probably has a defined size that seldom changes. Compare this with /dev/null which is also a file, but as a character special file , its size is not meaningful. Information in a computer file can consist of smaller packets of information (often called " records " or "lines") that are individually different but share some common traits. For example,
7700-423: The file. Some other examples of reasons for which files become corrupted include: Although file corruption usually happens accidentally, it may also be done on purpose as a mean of procrastination , as to fool someone else into thinking an assignment was ready at an earlier date, potentially gaining time to finish said assignment or making experiments, with the purpose of documenting the consequences when such file
7800-402: The files for their own use on an as-needed basis. The programmers who create the programs decide what files are needed, how they are to be used and (often) their names. In some cases, computer programs manipulate files that are made visible to the computer user. For example, in a word-processing program , the user manipulates document files that the user personally names. Although the content of
7900-517: The files without permission. The Pirate Bay does not store copies of the files on its own servers but does provide peer-to-peer links to other servers on which infringing copies were stored. Apparently, the theory of the prosecution was that the defendants, by their conduct, actively induced infringement. Under U.S. copyright law, this would be a so-called Grokster theory of infringement liability. The Swedish district court imposed damages of SEK 30 million ($ 3,600,000) and one-year prison sentences on
8000-442: The first silicon dioxide field effect transistors at Bell Labs, the first transistors in which drain and source were adjacent at the surface. Subsequently, a team demonstrated a working MOSFET at Bell Labs 1960. The MOSFET made it possible to build high-density integrated circuits , leading to what is known as the computer revolution or microcomputer revolution . A computer is a machine that manipulates data according to
8100-524: The first working transistor , the point-contact transistor , in 1947. In 1953, the University of Manchester built the first transistorized computer , the Manchester Baby . However, early junction transistors were relatively bulky devices that were difficult to mass-produce, which limited them to a number of specialised applications. In 1957, Frosch and Derick were able to manufacture
8200-428: The four defendants. "The defendants have furthered the crimes that the file sharers have committed," said district court judge Tomas Norstöm. He added, "They have been helpful to such an extent that they have entered into the field of criminal liability." "We are, of course, going to appeal," defense lawyer Per Samuelsson said. The Pirate Bay has 25 million users and is considered one of the biggest file-sharing websites in
8300-439: The hard disk drive. In Unix-like operating systems, many files have no associated physical storage device. Examples are /dev/null and most files under directories /dev , /proc and /sys . These are virtual files: they exist as objects within the operating system kernel. As seen by a running user program, files are usually represented either by a file control block or by a file handle . A file control block (FCB)
8400-418: The latter (afterwards deletion) method will have to only delete the files from the source directory that have already finished transferring. In modern computer systems, files are typically accessed using names ( filenames ). In some operating systems, the name is associated with the file itself. In others, the file is anonymous, and is pointed to by links that have names. In the latter case, a user can identify
8500-413: The name of the link with the file itself, but this is a false analogue, especially where there exists more than one link to the same file. Files (or links to files) can be located in directories. However, more generally, a directory can contain either a list of files or a list of links to files. Within this definition, it is of paramount importance that the term "file" includes directories. This permits
8600-460: The owner of these resources and the end user. It is typically offered as a service, making it an example of Software as a Service , Platforms as a Service , and Infrastructure as a Service , depending on the functionality offered. Key characteristics include on-demand access, broad network access, and the capability of rapid scaling. It allows individual users or small business to benefit from economies of scale . One area of interest in this field
8700-480: The platform they run on. For example, a geography application for Windows or an Android application for education or Linux gaming . Applications that run only on one platform and increase the desirability of that platform due to the popularity of the application, known as killer applications . A computer network, often simply referred to as a network, is a collection of hardware components and computers interconnected by communication channels that allow
8800-522: The protection of computer systems and networks. This includes information and data privacy , preventing disruption of IT services and prevention of theft of and damage to hardware, software, and data. Data science is a field that uses scientific and computing tools to extract information and insights from data, driven by the increasing volume and availability of data. Data mining , big data , statistics, machine learning and deep learning are all interwoven with data science. Information systems (IS)
8900-518: The purpose of a file at a glance. Some computer systems allow file names to contain spaces; others do not. Case-sensitivity of file names is determined by the file system . Unix file systems are usually case sensitive and allow user-level applications to create files whose names differ only in the case of characters. Microsoft Windows supports multiple file systems, each with different policies regarding case-sensitivity. The common FAT file system can have multiple files whose names differ only in case if
9000-606: The rules and data formats for exchanging information in a computer network, and provide the basis for network programming . One well-known communications protocol is Ethernet , a hardware and link layer standard that is ubiquitous in local area networks . Another common protocol is the Internet Protocol Suite , which defines a set of protocols for internetworking, i.e. for data communication between multiple networks, host-to-host data transfer, and application-specific data transmission formats. Computer networking
9100-513: The rules for how the bytes must be organized and interpreted meaningfully. For example, the bytes of a plain text file ( .txt in Windows) are associated with either ASCII or UTF-8 characters, while the bytes of image, video, and audio files are interpreted otherwise. Most file types also allocate a few bytes for metadata , which allows a file to carry some basic information about itself. Some file systems can store arbitrary (not interpreted by
9200-402: The same computer protects against failure of one disk, but if it is necessary to protect against failure or destruction of the entire computer, then copies of the files must be made on other media that can be taken away from the computer and stored in a safe, distant location. The grandfather-father-son backup method automatically makes three back-ups; the grandfather file is the oldest copy of
9300-454: The sharing of resources and information. When at least one process in one device is able to send or receive data to or from at least one process residing in a remote device, the two devices are said to be in a network. Networks may be classified according to a wide variety of characteristics such as the medium used to transport the data, communications protocol used, scale, topology , and organizational scope. Communications protocols define
9400-442: The study of these approaches. That is, the application of engineering to software. It is the act of using insights to conceive, model and scale a solution to a problem. The first reference to the term is the 1968 NATO Software Engineering Conference , and was intended to provoke thought regarding the perceived software crisis at the time. Software development , a widely used and more generic term, does not necessarily subsume
9500-446: The theory of computation and the design of computational systems. Its subfields can be divided into practical techniques for its implementation and application in computer systems , and purely theoretical areas. Some, such as computational complexity theory , which studies fundamental properties of computational problems , are highly abstract, while others, such as computer graphics , emphasize real-world applications. Others focus on
9600-611: The underlying hardware, rather than the contents stored on it, was denominated a "file". For example, the IBM 350 disk drives were denominated "disk files". The introduction, c. 1961 , by the Burroughs MCP and the MIT Compatible Time-Sharing System of the concept of a " file system " that managed several virtual "files" on one storage device is the origin of the contemporary denotation of
9700-580: The user uses a disk editor to edit the file names in the directory entries . User applications, however, will usually not allow the user to create multiple files with the same name but differing in case. Most computers organize files into hierarchies using folders, directories, or catalogs. The concept is the same irrespective of the terminology used. Each folder can contain an arbitrary number of files, and it can also contain other folders. These other folders are referred to as subfolders. Subfolders can contain still more files and folders and so on, thus building
9800-402: The word. Although the contemporary " register file " demonstrates the early concept of files, its use has greatly decreased. On most modern operating systems , files are organized into one-dimensional arrays of bytes . The format of a file is defined by its content since a file is solely a container for data. On some platforms the format is indicated by its filename extension , specifying
9900-440: The world. It is conceded that The Pirate Bay does not itself make copies or store files, but the court did not consider that fact dispositive. "By providing a website with ... well-developed search functions, easy uploading and storage possibilities, and with a tracker linked to the website, the accused have incited the crimes that the filesharers have committed," the court said in a statement. Computer file In computing ,
10000-488: Was the 1931 paper "The Use of Thyratrons for High Speed Automatic Counting of Physical Phenomena" by C. E. Wynn-Williams . Claude Shannon 's 1938 paper " A Symbolic Analysis of Relay and Switching Circuits " then introduced the idea of using electronics for Boolean algebraic operations. The concept of a field-effect transistor was proposed by Julius Edgar Lilienfeld in 1925. John Bardeen and Walter Brattain , while working under William Shockley at Bell Labs , built
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