A bitstream or bit stream is a time series of bits. A bytestream is a series of bytes, typically of 8 bits each, and can be regarded as a special case of a bitstream.

Bitstreams are used extensively in telecommunications and computing: for example, the SDH communications technology transports synchronous bitstreams, and the TCP communications protocol transports a bytestream without synchronous timing.

When a bitstream is captured and stored on a computer storage media, a computer file is created.

Bitstream is also the name of a type foundry, see Bitstream Inc.