A byte is the basic unit of measurement of information storage in computer science. In many computer architectures it is a unit of memory addressing, most often consisting of eight bits. A byte is one of the basic integral data types in some programming languages, especially system programming languages.

A byte is an ordered collection of bits, with each bit denoting a single binary value of 1 or 0. The size of a byte can vary and is generally determined by the underlying computer operating system or hardware, although the 8-bit byte is the standard in modern systems.
Source: Wikipedia