In computing, the term stream is used in a number of ways, in all cases referring to a sequence of data elements made available over time. A stream can be thought of as a conveyor belt that allows items to be processed one at a time rather than in large batches.
On Unix and related systems based on the C language, a stream is a source or sink of data, usually individual bytes or characters. Streams are an abstraction used when reading or writing files, or communicating over network sockets. The standard streams are three streams made available to all programs.
Pipelines can also be understood as streams as well as any unlimited (non-packaged) information that is inserted by a device.
Filesystems can store multiple named independent streams against a single filename. There is one main stream that makes up the normal file data. Additional streams can be used to store icons, summary and indexing information, zone information (i.e., where the file was downloaded from), etc.