Information technology

Information technology (IT) is a branch of engineering dealing with the use of computers and telecommunications equipment to store, retrieve, transmit and manipulate data.[1] The Information Technology Association of America has defined IT as “the study, design, development, application, implementation, support or management of computer-based information systems”.[2] The term is commonly used as a synonym for computers and computer networks, but it also encompasses other information distribution technologies such as television and telephones.[3]

Humans have been storing, retrieving, manipulating and communicating information since the Sumerians in Mesopotamia developed writing in about 3000 BC,[4] but the term “information technology” in its modern sense first appeared in a 1958 article published in the Harvard Business Review; authors Leavitt and Whisler commented that “the new technology does not yet have a single established name. We shall call it information technology (IT).”[5] Based on the storage and processing technology employed, it is possible to distinguish four distinct phases of IT development: pre-mechanical (3000 BC – 1450 AD), mechanical (1450–1840), electromechanical (1840–1940) and electronic.[4] This article focuses on the latter of those periods, which began in about 1940.

History of computers

Early electronic computers such as Colossus made use of punched tape, a long strip of paper on which data was represented by a series of holes, a technology now obsolete.[12] Electronic data storage as used in modern computers dates from the Second World War, when a form of delay line memory was developed to remove the clutter from radar signals, the first practical application of which was the mercury delay line.[13] The first random-access digital storage device was the Williams tube, based on a standard cathode ray tube,[14] but the information stored in it and delay line memory was volatile in that it had to be continuously refreshed, and thus was lost once power was removed. The earliest form of non-volatile computer storage was the magnetic drum, invented in 1932[15] and used in the Ferranti Mark 1, the world’s first commercially available general-purpose electronic computer.[16]

Most digital data today is still stored magnetically on devices such as hard disk drives, or optically on media such as CD-ROMs.[17] It has been estimated that the worldwide capacity to store information on electronic devices grew from less than 3 exabytes in 1986 to 295 exabytes in 2007,[18] doubling roughly every 3 years.

Databases
Database management systems emerged in the 1960s to address the problem of storing and retrieving large amounts of data accurately and quickly. One of the earliest such systems was IBM’s Information Management System (IMS),[20] which is still widely deployed more than 40 years later.[21] IMS stores data hierarchically,[20] but in the 1970s Ted Codd proposed an alternative relational storage model based on set theory and predicate logic and the familiar concepts of tables, rows and columns. The first commercially available relational database management system (RDBMS) was available from Oracle in 1980.[22]

All database management systems consist of a number of components that together allow the data they store to be accessed simultaneously by many users while maintaining its integrity. A characteristic of all databases is that the structure of the data they contain is defined and stored separately from the data itself, in a database schema.[20]

The extensible markup language (XML) has become a popular format for data representation in recent years. Although XML data can be stored in normal file systems, it is commonly held in relational databases to take advantage of their “robust implementation verified by years of both theoretical and practical effort”.[23] As an evolution of the Standard Generalized Markup Language (SGML), XML’s text-based structure offers the advantage of being both machine and human-readable.[24]

Data retrieval

The relational database model introduced a programming language independent Structured Query Language (SQL), based on relational algebra.[22]

The terms “data” and “information” are not synonymous. Anything stored is data, but it only becomes information when it is organised and presented meaningfully.[25] Most of the world’s digital data is unstructured, stored in a variety of different formats[26][a] even within a single organisation. Data warehouses began to be developed in the 1980s to integrate these disparate stores. They typically contain data extracted from various sources, including external sources such as the Internet, organised in such a way as to facilitate decision support systems (DSS).[27]

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