Ination technology.doc

Information technologyFrom Wikipedia, the free encyclopedia(Redirected fromIT)Not to be confused withInformatics.IT redirects here. For other uses, seeIt (disambiguation).Information scienceGeneral aspects Information accessInformation architecture Information management Information retrieval Information seekingInformation society Knowledge organizationOntologyTaxonomy Philosophy of information Science, technology and societyRelated fields and sub-fields BibliometricsCategorization CensorshipClassification Computer data storageCultural studies Data modelingInformatics Information technology Intellectual freedom Intellectual propertyMemory Library and information science PreservationPrivacy Quantum information science Information science portal v t eInformation technology(IT) is the application ofcomputersandinternetto store, study, retrieve, transmit, and manipulatedata,1orinformation, often in the context of a business or other enterprise.2IT is considered a subset ofinformation and communications technology(ICT). In 2012, Zuppo proposed an ICT hierarchy where each hierarchy level contain some degree of commonality in that they are related to technologies that facilitate the transfer of information and various types of electronically mediated communications.3Business/IT was one level of the ICT hierarchy.The term is commonly used as asynonymfor computers and computer networks, but it also encompasses otherinformationdistribution technologies such as television and telephones. Severalindustriesare associated with information technology, includingcomputer hardware,software,electronics,semiconductors,internet,telecom equipment,engineering,healthcare,e-commerce, and computer services.4aHumans have been storing, retrieving, manipulating, and communicating information since theSumeriansinMesopotamiadevelopedwritingin about 3000BC,6but the terminformation technologyin its modern sense first appeared in a 1958 article published in theHarvard Business Review; authorsHarold J. Leavittand Thomas L. Whisler commented that the new technology does not yet have a single established name. We shall call it information technology (IT). Their definition consists of three categories: techniques for processing, the application of statistical and mathematical methods to decision-making, and the simulation of higher-order thinking through computer programs.7Based on the storage and processing technologies employed, it is possible to distinguish four distinct phases of IT development: pre-mechanical (3000BC 1450AD), mechanical (14501840), electromechanical (18401940), electronic (1940present),6and moreover,IT as a service. This article focuses on the most recent period (electronic), which began in about 1940.Contentshide 1History of computer technology 2Data processingo 2.1Data storage 2.1.1Databaseso 2.2Data retrievalo 2.3Data transmissiono 2.4Data manipulation 3Perspectiveo 3.1Academic perspectiveo 3.2Commercial and employment perspectiveo 3.3Ethical perspective 4See also 5References 6Further reading 7External linksHistory of computer technologyeditZuse Z3 replica on display atDeutsches MuseuminMunich. The Zuse Z3 is the first programmable computer.Main article:History of computing hardwareDevices have been used to aid computation for thousands of years, probably initially in the form of atally stick.8TheAntikythera mechanism, dating from about the beginning of the first century BC, is generally considered to be the earliest known mechanicalanalog computer, and the earliest known geared mechanism.9Comparable geared devices did not emerge in Europe until the 16th century,10and it was not until 1645 that the firstmechanical calculatorcapable of performing the four basic arithmetical operations was developed.11Electronic computers, using eitherrelaysorvalves, began to appear in the early 1940s. The electromechanicalZuse Z3, completed in 1941, was the worlds firstprogrammablecomputer, and by modern standards one of the first machines that could be considered a completecomputingmachine.Colossus, developed during the Second World War to decryptGermanmessages was the firstelectronicdigitalcomputer. Although it wasprogrammable, it was not general-purpose, being designed to perform only a single task. It also lacked the ability to store its program in memory; programming was carried out using plugs and switches to alter the internal wiring.12The first recognisably modern electronic digitalstored-program computerwas theManchester Small-Scale Experimental Machine(SSEM), which ran its first program on 21 June 1948.13The development oftransistorsin the late 1940s atBell Laboratoriesallowed a new generation of computers to be designed with greatly reduced power consumption. The first commercially available stored-program computer, theFerranti Mark I, contained 4050 valves and had a power consumption of 25 kilowatts. By comparison the first transistorised computer, developed at the University of Manchester and operational by November 1953, consumed only 150 watts in its final version.14Data processingeditData storageeditPunched tapes that were used in early computers to represent data.Main article:Data storage deviceEarly electronic computers such asColossusmade use ofpunched tape, a long strip of paper on which data was represented by a series of holes, a technology now obsolete.15Electronic data storage, which is used in modern computers, dates from World War II, when a form ofdelay line memorywas developed to remove the clutter fromradarsignals, the first practical application of which was the mercury delay line.16The firstrandom-accessdigital storage device was theWilliams tube, based on a standardcathode ray tube,17but 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 themagnetic drum, invented in 193218and used in theFerranti Mark 1, the worlds first commercially available general-purpose electronic computer.19IBM introduced the firsthard disk drivein 1956, as a component of their305 RAMACcomputer system.20Most digital data today is still stored magnetically on hard disks, or optically on media such asCD-ROMs.21Until 2002 most information was stored onanalog devices, but that year digital storage capacity exceeded analog for the first time. As of 2007 almost 94% of the data stored worldwide was held digitally:2252% on hard disks, 28% on optical devices and 11% on digital magnetic tape. It has been estimated that the worldwide capacity to store information on electronic devices grew from less than 3exabytesin 1986 to 295 exabytes in 2007,23doubling roughly every 3 years.24DatabaseseditMain article:DatabaseDatabase management systems emerged in the 1960s25to address the problem of storing and retrieving large amounts of data accurately and quickly. One of the earliest such systems wasIBMsInformation Management System(IMS),25which is still widely deployed more than 40 years later.26IMS stores datahierarchically,25but in the 1970sTed Coddproposed an alternative relational storage model based onset theoryandpredicate logicand the familiar concepts of tables, rows and columns. The first commercially availablerelational database management system(RDBMS) was available fromOraclein 1980.27All 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 adatabase schema.25Theextensible markup language(XML) has become a popular format for data representation in recent years. Although XML data can be stored in normalfile systems, it is commonly held inrelational databasesto take advantage of their robust implementation verified by years of both theoretical and practical effort.28As an evolution of theStandard Generalized Markup Language(SGML), XMLs text-based structure offers the advantage of being both machine and human-readable.29Data retrievaleditThe relational database model introduced a programming-language independentStructured Query Language(SQL), based onrelational algebra.27The terms data and information are not synonymous. Anything stored is data, but it only becomes information when it is organized and presented meaningfully.30Most of the worlds digital data is unstructured, and stored in a variety of different physical formats31beven within a single organization.Data warehousesbegan 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, organized in such a way as to facilitatedecision support systems(DSS).32Data transmissioneditData transmissionhas three aspects: transmission, propagation, and reception.33It can be broadly categorized asbroadcasting, in which information is transmitted unidirectionally downstream, ortelecommunications, with bidirectional upstream and downstream channels.23XML has been increasingly employed as a means of data interchange since the early 2000s,34particularly for machine-oriented interactions such as those involved in web-orientedprotocolssuch asSOAP,29describing data-in-transit rather than. data-at-rest.34One of the challenges of such usage is converting data from relational databases into XMLDocument Object Model(DOM) structures.35Data manipulationeditHilbert and Lopez identify the exponential pace of technological change (a kind ofMoores law): machines application-specific capacity to compute information per capita roughly doubled every 14 months between 1986 and 2007; the per capita capacity of the worlds general-purpose computers doubled every 18 months during the same two decades; the global telecommunication capacity per capita doubled every 34 months; the worlds storage capacity per capita required roughly 40 months to double (every 3 years); and per capita broadcast information has doubled every 12.3 years.23Massive amounts of data are stored worldwide every day, but unless it can be analysed and presented effectively it essentially resides in what have been called data tombs: data archives that are seldom visited.36To address that issue, the field ofdata mining the process of discovering interesting patterns and knowledge from large amounts of data37 emerged in the late 1980s.38PerspectiveeditAcademic perspectiveeditIn an academic context, the Association for Computing Machinery defines IT as undergraduate degree programs that prepare students to meet the computer technology needs of business, government, healthcare, schools, and other kinds of organizations. IT specialists assume responsibility for selecting hardware and software products appropriate for an organization, integrating those products with organizational needs and infrastructure, and installing, customizing, and maintaining those applications for the organizations computer users.39Commercial and employment perspectiveeditIn a business context, theInformation Technology Association of Americahas defined information technology as the study, design, development, application, implementation, support or management of computer-basedinformation systems.40The responsibilities of those working in the field include network administration, software development and installation, and the planning and management of an organizations technology life cycle, by which hardware and software are maintained, upgraded and replaced.The business value of information technology lies in the automation of business processes, provision of information for decision making, connect