Various kinds of input and output devices are available, depending on the requirements of the user and the specifics of the application.

The best-known input device is the keyboard, which is composed of numerous typewriterlike keys, arranged in a configuration similar to that of a typewriter. In addition to the ordinary keys associated with text characters, keyboards usually have special keys (e.g. Ctrl, Alt, etc.) designed to represent input signals with special meanings. Most keyboards have the QWERTY (also called 'Q') layout, which was designed with the English language in mind. (It is called QWERTY because of the ordering of the letters on the keyboard's topmost row of letters.) Some other languages have their own keyboard layouts. French keyboards have the AZERT layout. The corresponding layout for Turkish has the letter 'F' at the beginning of the first row. 'Turkish Q' keyboards, where the Turkish letters not present in the English alphabet are placed around the keys in the standard QWERTY layout are also available.

A mouse is an input device which is able to send signals about the changes in its own physical coordinates on the table to the computer. A computer with the appropriate software can use this setup to provide an environment where the user can change the position of a symbol on the screen by moving the mouse in the required relative direction.

Optical character recognition (OCR) equipment are used to input 'optical' data like 'dark-bubble' answers to multiple-choice questions, or the bar codes on several items indicating, among other things, their prices.

Research is going on to come up with more reliable technologies for voice and handwriting recognition by computers. Obviously, these involve specialized input devices.

Output devices can be of two kinds; those that produce hard copy (information recorded permanently on a medium like paper or microfilm,) or soft copy, e.g. display output.

There are two kinds of display devices: Display terminals, which are combined input/output devices consisting of a display device and a keyboard, and monitors, which consist only of a screen. The highlighting symbol which appears on the screen position where the next character typed in from the keyboard will appear is called the cursor. The resolution of a display device is a measure of the 'sharpness' of the image on the screen. Images are formed by lighting up tiny dots called pixels ('picture elements') on the screen. If a screen has more pixels per unit area, its image will be clearer, i.e. its resolution will be high. Resolutions of 640 by 480 (meaning that there are 480 rows covering the screen, each containing 640 pixels) are typical.

Display devices can be monochrome (i.e. have only one foreground color,) or color (i.e. with eight or more colors on the screen at the same time.)

Display devices can be CRT's (cathode-ray tubes) which employ the same picture-generating technology as standard TV sets, or flat-panel displays, which are slimmer, employing newer technologies.

Impact printing is a conventional printing technology where the images on the paper are formed by a metal hammer which causes an ink ribbon to come into contact with the paper. In printers using a solid-font mechanism, the shapes of all the characters that the printer can output are embossed on metal, and the printer selects and strikes the appropriate character according to the signal it receives from the computer. Impact dot-matrix printers have a single print head which contains one or more vertical rows of pins, some of which are activated to form part of the image currently being printed. Unlike the solid-font approach, each character printed by a dot-matrix printer is a combination of several dots of ink.

In nonimpact printing, there is no physical contact between the printing mechanism and the paper. Different methods of nonimpact printing are electrothermal printing, used by fax machines, which involves burning the images onto a special kind of paper, ink-jet printing, where small dots of electrically charged ink are sprayed onto the paper, and laser printing, in which a laser beam is used to charge parts of a platen, toner gets 'stuck' to these charged parts, and the paper is pressed to this platen to form the image. All these employ the dot-matrix idea, so practically any image can be produced using them.

If great amounts of data are to be printed, one needs high-speed printers, like line printers, which can print a line at a time, or page printers, which can produce a page at a time. These are capable of delivering hundreds of pages per minute.

Plotters are output devices whose primary purpose is to produce graphic output such as charts, maps, etc.

Voice-output devices enable the computer to produce words in natural language; as of 1998, the quality of the speech produced is not excellent.

Film recorders are cameralike devices which record computer-generated images directly onto film media.

Many other specialized input and output devices are available.