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What Does Input/Output Mean?

Input/output (I/O), in computing, is a communication process between a computer and the outside world.


At its most basic level, an information system (IS), such as a software application, is installed on a computer and its users in the outside world operate the computer to get solutions to problems. Input refers to the signals or instructions sent to the computer. Output refers to the signals sent out from the computer.

This term is also known as I/O operations, which references the input and output actions.

Techopedia Explains Input/Output

There are input and output operations performed in a computer context everywhere. Simple common I/O devices include a mouse, keyboard, monitor and printer.

Following are the major contexts for the I/O term:

  1. I/O Interfaces: These provide a way to interact with computer hardware. The interface of each device is capable of encoding and decoding the I/O signals in an understandable form for both input and output devices.
  2. Programmable Application I/O: Many applications are integrated with operating systems (OSs) providing run time inputs and output simultaneously. The best examples are C, C++ and Java programming applications, which have built-in libraries used for I/O operations. Programs are written so that one library file is used as input while the output is shown to user. In programming, this concept is known as file handling.
  3. Memory Addressing I/O: Computer memory contains blocks to store the applications/processes for processing. Many addressing mechanisms are used for this purpose; each uses I/O operations in some context. Memory addressing using memory I/O operations are indexed addressing and immediate-addressing.

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Margaret Rouse
Technology Expert
Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.