Data (computing) in the context of "Computer security"

In computing, a database is an organized collection of data or a type of data store based on the use of a database management system (DBMS), the software that interacts with end users, applications, and the database itself to capture and analyze the data. The DBMS additionally encompasses the core facilities provided to administer the database. The sum total of the database, the DBMS and the associated applications can be referred to as a database system. Often the term "database" is also used loosely to refer to any of the DBMS, the database system or an application associated with the database.

Before digital storage and retrieval of data have become widespread, index cards were used for data storage in a wide range of applications and environments: in the home to record and store recipes, shopping lists, contact information and other organizational data; in business to record presentation notes, project research and notes, and contact information; in schools as flash cards or other visual aids; and in academic research to hold data such as bibliographical citations or notes in a card file. Professional book indexers used index cards in the creation of book indexes until they were replaced by indexing software in the 1980s and 1990s.

A computer file is a collection of 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 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.

An electronic document is a document that can be sent through non-physical means, such as telex, email, and the internet. Originally, any computer data were considered as something internal—the final data output was always on paper. However, the development of computer networks has made it so that in most cases it is much more convenient to distribute electronic documents than printed ones. The improvements in electronic visual display technologies made it possible to view documents on a screen instead of printing them (thus saving paper and the space required to store the printed copies). However, using electronic documents for the final presentation instead of paper has created the problem of multiple incompatible file formats. Even plain text computer files are not free from this problem—e.g. under MS-DOS, most programs could not work correctly with UNIX-style text files (see newline), and for non-English speakers, the different code pages always have been a source of trouble.

Even more problems are connected with complex file formats of various word processors, spreadsheets, and graphics software. To alleviate the problem, many software companies distribute free file viewers for their proprietary file formats (one example is Adobe's Acrobat Reader). The other solution is the development of standardized non-proprietary file formats (such as HTML and OpenDocument), and electronic documents for specialized uses have specialized formats—the specialized electronic articles in physics use TeX or PostScript.

In telecommunications, packet switching is a method of grouping data into short messages in fixed format, i.e., packets, that are transmitted over a telecommunications network. Packets consist of a header and a payload. Data in the header is used by networking hardware to direct the packet to its destination, where the payload is extracted and used by an operating system, application software, or higher layer protocols. Packet switching is the primary basis for data communications in computer networks worldwide.

During the early 1960s, American engineer Paul Baran developed a concept he called distributed adaptive message block switching as part of a research program at the RAND Corporation, funded by the United States Department of Defense. His proposal was to provide a fault-tolerant, efficient method for communication of voice messages using low-cost hardware to route the message blocks across a distributed network. His ideas contradicted then-established principles of pre-allocation of network bandwidth, exemplified by the development of telecommunications in the Bell System. The new concept found little resonance among network implementers until the independent work of Welsh computer scientist Donald Davies at the National Physical Laboratory beginning in 1965. Davies developed the concept for data communication using software switches in a high-speed computer network and coined the term packet switching. His work inspired numerous packet switching networks in the decade following, including the incorporation of the concept into the design of the ARPANET in the United States and the CYCLADES network in France. The ARPANET and CYCLADES were the primary precursor networks of the modern Internet.

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.

A download is a file offered for downloading or that has been downloaded, or the process of receiving such a file.

In telecommunications and computer networking, a network packet is a formatted unit of data carried by a packet-switched network. A packet consists of control information and user data; the latter is also known as the payload. Control information provides data for delivering the payload (e.g., source and destination network addresses, error detection codes, or sequencing information). Typically, control information is found in packet headers and trailers.

In packet switching, the bandwidth of the transmission medium is shared between multiple communication sessions, in contrast to circuit switching, in which circuits are preallocated for the duration of one session and data is typically transmitted as a continuous bit stream.