Berkeley sockets is an application programming interface (API) for Internet sockets and Unix domain sockets, used for inter-process communication (IPC). It is commonly implemented as a library of linkable modules. It originated with the 4.2BSD Unix operating system, which was released in 1983.
A socket is an abstract representation (handle) for the local endpoint of a network communication path. The Berkeley sockets API represents it as a file descriptor (file handle) in the Unix philosophy that provides a common interface for input and output to streams of data.
Berkeley sockets evolved with little modification from a de facto standard into a component of the POSIX specification. The term POSIX sockets is essentially synonymous with Berkeley sockets, but they are also known as BSD sockets, acknowledging the first implementation in the Berkeley Software Distribution.

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