在计算机科学里面，字串流（英语：stream），又译串流，这个词有很多用法。所有这一些用法都是代表一个包含数据的串行。我们可以将字串流想做是一个允许数据一个接一个，而非将数据报作一整个，来进行处理的输送带，。

In computer science, a stream is a sequence of data elements made available over time. A stream can be thought of as items on a conveyor belt being processed one at a time rather than in large batches

Streams are processed differently from batch data – normal functions cannot operate on streams as a whole, as they have potentially unlimited data, and formally, streams are codata (potentially unlimited), not data (which is finite). Functions that operate on a stream, producing another stream, are known as filters, and can be connected in pipelines, analogously to function composition. Filters may operate on one item of a stream at a time, or may base an item of output on multiple items of input, such as a moving average.