一个比特流（bitstream或bit stream）是一个比特的串行。一个字节流则是一个字节的串行，一般来说一个字节是8个比特。也可以被视为是一种特殊的比特流。

比特流在远程通信和计算这些领域里面被广泛的使用：举例来说，同步光网络通信科技会传输同步比特流, and the TCP则传输一个没有时间同步的字节流。

当一个比特流被访问进电脑的记忆设备里面并且记忆起来，会创造出一个电脑文件。

比特流这个词常被使用于形容FPGA（组件可编程逻辑门数组）设置所需要使用的数据。这种用法或许是起源于一般在设置FPGA时常用的方法都是使用一个连续的字节合，例如说使用串行化的PROM or flash芯片，虽然大多数的FPGA也支持平行比特（byte-parallel）的输入方法。至于对特定FPGA芯片的比特流设置细节一般则被认为是属于该FPGA芯片贩售商的所有权。

A bitstream or bit stream is a sequence of bits.

A bytestream is a sequence of bytes. Typically, each byte is from a range of 256 distinct values (octets), and so the term octet stream is sometimes used to refer to the same thing. An octet may be encoded as a sequence of 8 bits in multiple different ways (see endianness) so there is no unique and direct translation between bytestreams and bitstreams. In practice, bitstreams are not used directly to encode bytestreams; a communication channel may use a signalling method that does not directly translate to bits (for instance, by transmitting signals of multiple frequencies) and typically also encodes other information such as framing and error correction together with its data.