What is Computer?
[[File:IBM System360 Mainframe.jpg|thumb|This is an [[IBM System/360]].]] A '''computer''' is a [[machine]] that uses [[electronics]] to input, process, store, and output [[data]]. Data is information such as numbers, words, and lists. Input of data means to read information from a keyboard, a storage device like a [[hard drive]], or a [[sensor]]. The computer processes or changes the data by following the instructions in [[software]] programs. A computer program is a list of instructions the computer has to perform. Programs usually perform mathematical calculations, modify data, or move it around. The data is then saved on a storage device, shown on a [[computer display|display]], or sent to another computer. Computers can be connected together to form a [[computer network|network]] such as the [[internet]], allowing the computers to communicate with each other. The [[Central processing unit|processor]] of a computer is made from [[integrated circuits]] (chips) that contains many [[transistors]]. Most computers are [[digital]], which means that they represent information using [[binary]] [[digit]]s, or [[bit]]s. Computers come in different shapes and sizes, depending on the brand, model, and purpose. They range from small computers, such as smartphones and [[laptop]]s, to large computers, such as [[supercomputer]]s. == Characteristics == Two things that define a computer are that it responds to a specific [[instruction set]] in a well-defined manner, and that it can execute a stored list of instructions called a [[Computer program|program]]. There are four main actions in a computer: [[Input device|inputting]], [[Computer memory|storing]], [[Output device|outputting]] and processing. Modern computers can do billions of calculations in a second. Being able to calculate many times per second allows modern computers to multi-task, which means they can do many different tasks at the same time. Computers do many different jobs where [[automation]] is useful. Some examples are controlling [[traffic light]]s, vehic