In computing, input/output, or I/O, refers to the communication between an information processing system (such as a computer), and the outside world, possibly a human, or another information processing system.
(Source: Wikipedia [Input/Output])
I/O includes tasks such as:
- Reading and writing files (file-io)
- Interacting with a user through a command-line terminal session (stdin / stdout / stderr)
- Connecting programs so that one sends its output to the next (pipes)
- Sending data over a network in packets or as a data stream (networking)
For the Io language, see iolanguage