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Information technology (IT) is the use of computers to store, retrieve, transmit, and manipulate dataor information. IT is typically used within the context of business operations as opposed to personal or entertainment technologies. IT is considered to be a subset of information and communications technology (ICT). An information technology system (IT system) is generally an information system, a communications system or, more specifically speaking, a computer system – including all hardware, software and peripheral equipment – operated by a limited group of users.
Humans have been storing, retrieving, manipulating, and communicating information since the Sumerians in Mesopotamia developed writing in about 3000 BC, but the term information technology in its modern sense first appeared in a 1958 article published in the Harvard Business Review ; authors Harold J. Leavitt and 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.
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. Several products or services within an economy are associated with information technology, including computer hardware, software, electronics, semiconductors, internet, telecom equipment, and e-commerce.
Based on the storage and processing technologies 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 (1940–present). This article focuses on the most recent period (electronic).
Devices have been used to aid computation for thousands of years, probably initially in the form of a tally stick.The Antikythera mechanism, dating from about the beginning of the first century BC, is generally considered to be the earliest known mechanical analog computer, and the earliest known geared mechanism. Comparable geared devices did not emerge in Europe until the 16th century, and it was not until 1645 that the first mechanical calculator capable of performing the four basic arithmetical operations was developed.
Electronic computers, using either relays or valves, began to appear in the early 1940s. The electromechanical Zuse Z3, completed in 1941, was the world's first programmable computer, and by modern standards one of the first machines that could be considered a complete computing machine. Colossus, developed during the Second World War to decrypt German messages, was the first electronic digital computer. Although it was programmable, 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.The first recognisably modern electronic digital stored-program computer was the Manchester Baby, which ran its first program on 21 June 1948.
The development of transistors in the late 1940s at Bell Laboratories allowed a new generation of computers to be designed with greatly reduced power consumption. The first commercially available stored-program computer, the Ferranti Mark I, contained 4050 valves and had a power consumption of 25 kilowatts. By comparison, the first transistorized computer developed at the University of Manchester and operational by November 1953, consumed only 150 watts in its final version.
Several later breakthroughs in semiconductor technology include the integrated circuit (IC) invented by Jack Kilby at Texas Instruments and Robert Noyce at Fairchild Semiconductor in 1959, the metal-oxide-semiconductor field-effect transistor (MOSFET) invented by Mohamed Atalla and Dawon Kahng at Bell Laboratories in 1959, and the microprocessor invented by Ted Hoff, Federico Faggin, Masatoshi Shima and Stanley Mazor at Intel in 1971. These important inventions led to the development of the personal computer (PC) in the 1970s, and the emergence of information and communications technology (ICT).
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.Electronic data storage, which is used in modern computers, dates from World War II, 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. The first random-access digital storage device was the Williams tube, based on a standard cathode ray tube, 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 and used in the Ferranti Mark 1, the world's first commercially available general-purpose electronic computer.
IBM introduced the first hard disk drive in 1956, as a component of their 305 RAMAC computer system. 6 Most digital data today is still stored magnetically on hard disks, or optically on media such as CD-ROMs. :4–5 Until 2002 most information was stored on analog 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: 52% 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 3 exabytes in 1986 to 295 exabytes in 2007, doubling roughly every 3 years.:
Database Management Systems (DMS) emerged in the 1960s to address the problem of storing and retrieving large amounts of data accurately and quickly. An early such systems was IBM's Information Management System (IMS),which is still widely deployed more than 50 years later. IMS stores data hierarchically, 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. In 1981, the first commercially available relational database management system (RDBMS) was released by Oracle.
All DMS consist of components, they allow the data they store to be accessed simultaneously by many users while maintaining its integrity.All databases are common in one point that the structure of the data they contain is defined and stored separately from the data itself, in a database schema.
In recent years, the extensible markup language (XML) has become a popular format for data representation. 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".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.
The relational database model introduced a programming-language independent Structured Query Language (SQL), based on relational algebra.
The terms "data" and "information" are not synonymous. Anything stored is data, but it only becomes information when it is organized and presented meaningfully. 1–9 Most of the world's digital data is unstructured, and stored in a variety of different physical formats even within a single organization. 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, organized in such a way as to facilitate decision support systems (DSS). :4–6:
Data transmission has three aspects: transmission, propagation, and reception.It can be broadly categorized as broadcasting, in which information is transmitted unidirectionally downstream, or telecommunications, with bidirectional upstream and downstream channels.
XML has been increasingly employed as a means of data interchange since the early 2000s, ... data-at-rest".particularly for machine-oriented interactions such as those involved in web-oriented protocols such as SOAP, describing "data-in-transit rather than
Hilbert and Lopez identify the exponential pace of technological change (a kind of Moore's 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 world's general-purpose computers doubled every 18 months during the same two decades; the global telecommunication capacity per capita doubled every 34 months; the world's storage capacity per capita required roughly 40 months to double (every 3 years); and per capita broadcast information has doubled every 12.3 years.
Massive 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". – "the process of discovering interesting patterns and knowledge from large amounts of data" – emerged in the late 1980s.To address that issue, the field of data mining
In 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 organization’s computer users."
Companies in the information technology field are often discussed as a group as the "tech sector" or the "tech industry".
Many companies now have IT departments for managing the computers, networks, and other technical areas of their businesses.
In a business context, the Information Technology Association of America has defined information technology as "the study, design, development, application, implementation, support or management of computer-based information systems". [ page needed ] The responsibilities of those working in the field include network administration, software development and installation, and the planning and management of an organization's technology life cycle, by which hardware and software are maintained, upgraded and replaced.
The field of information ethics was established by mathematician Norbert Wiener in the 1940s. 9 Some of the ethical issues associated with the use of information technology include: :20–21:
Computing is any activity that uses computers to manage, process, and communicate information. It includes development of both hardware and software. Computing is a critical, integral component of modern industrial technology. Major computing disciplines include computer engineering, software engineering, computer science, information systems, and information technology.
Computer science is the study of processes that interact with data and that can be represented as data in the form of programs. It enables the use of algorithms to manipulate, store, and communicate digital information. A computer scientist studies the theory of computation and the design of software systems.
A database is an organized collection of data, generally stored and accessed electronically from a computer system. Where databases are more complex they are often developed using formal design and modeling techniques.
An object database is a database management system in which information is represented in the form of objects as used in object-oriented programming. Object databases are different from relational databases which are table-oriented. Object-relational databases are a hybrid of both approaches.
SQL is a domain-specific language used in programming and designed for managing data held in a relational database management system (RDBMS), or for stream processing in a relational data stream management system (RDSMS). It is particularly useful in handling structured data, i.e. data incorporating relations among entities and variables.
Db2 is a family of data management products, including database servers, developed by IBM. They initially supported the relational model, but were extended to support object-relational features and non-relational structures like JSON and XML. The brand name was originally styled as DB/2, then DB2 until 2017 and finally changed to its present form.
A stored-program computer is a computer that stores program instructions in electronic memory. This contrasts with machines where the program instructions are stored on plugboards or similar mechanisms.
Online analytical processing, or OLAP, is an approach to answer multi-dimensional analytical (MDA) queries swiftly in computing. OLAP is part of the broader category of business intelligence, which also encompasses relational databases, report writing and data mining. Typical applications of OLAP include business reporting for sales, marketing, management reporting, business process management (BPM), budgeting and forecasting, financial reporting and similar areas, with new applications emerging, such as agriculture.
The von Neumann architecture—also known as the von Neumann model or Princeton architecture—is a computer architecture based on a 1945 description by Hungarian-American mathematician and physicist John von Neumann and others in the First Draft of a Report on the EDVAC. That document describes a design architecture for an electronic digital computer with these components:
The Department of Computer Science at the University of Manchester is the longest established department of Computer Science in the United Kingdom and one of the largest. It is located in the Kilburn building on the Oxford Road and currently has over 800 students taking a wide range of undergraduate and postgraduate courses and 60 full-time academic staff.
The Manchester Baby, also called the small-scale experimental machine (SSEM), was the first electronic stored-program computer, and built at the University of Manchester, UK, by Frederic C. Williams, Tom Kilburn, and Geoff Tootill, and ran its first program on 21 June 1948, seventy-one years ago.
Data modeling in software engineering is the process of creating a data model for an information system by applying certain formal techniques.
Enterprise content management (ECM) extends the concept of content management by adding a timeline for each content item and, possibly, enforcing processes for its creation, approval and distribution. Systems using ECM generally provide a secure repository for managed items, analog or digital. They also include one methods for importing content to bring manage new items, and several presentation methods to make items available for use. Although ECM content may be protected by digital rights management (DRM), it is not required. ECM is distinguished from general content management by its cognizance of the processes and procedures of the enterprise for which it is created.
Entity–attribute–value model (EAV) is a data model to encode, in a space-efficient manner, entities where the number of attributes that can be used to describe them is potentially vast, but the number that will actually apply to a given entity is relatively modest. Such entities correspond to the mathematical notion of a sparse matrix.
Cloud storage is a model of computer data storage in which the digital data is stored in logical pools. The physical storage spans multiple servers, and the physical environment is typically owned and managed by a hosting company. These cloud storage providers are responsible for keeping the data available and accessible, and the physical environment protected and running. People and organizations buy or lease storage capacity from the providers to store user, organization, or application data.
The Manchester computers were an innovative series of stored-program electronic computers developed during the 30-year period between 1947 and 1977 by a small team at the University of Manchester, under the leadership of Tom Kilburn. They included the world's first stored-program computer, the world's first transistorised computer, and what was the world's fastest computer at the time of its inauguration in 1962.
The Manchester Mark 1 was one of the earliest stored-program computers, developed at the Victoria University of Manchester from the Manchester Baby. It was also called the Manchester Automatic Digital Machine, or MADM. Work began in August 1948, and the first version was operational by April 1949; a program written to search for Mersenne primes ran error-free for nine hours on the night of 16/17 June 1949.
Shadow Tables are objects in computer science used to improve the way machines, networks and programs handle information. More specifically, a shadow table is an object that is read and written by a processor and contains data similar to its primary table, which is the table it's "shadowing". Shadow tables usually contain data that is relevant to the operation and maintenance of its primary table, but not within the subset of data required for the primary table to exist. Shadow tables are related to the data type "trails" in data storage systems. Trails are very similar to shadow tables but instead of storing identically formatted information that is different, they store a history of modifications and functions operated on a table.
Martin L. Kersten is a computer scientist with research focus on database architectures, query optimization and their use in scientific databases. He is an architect of the MonetDB system, an open-source column store for data warehouses, online analytical processing (OLAP) and geographic information systems (GIS). He has been (co-) founder of several successful spin-offs of the Centrum Wiskunde & Informatica (CWI).
Commonly a synonym for computers and computer networks but more broadly designating any technology that is used to generate, store, process, and/or distribute information electronically, including television and telephone.
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