A socket generally designates a cavity or region used for fitting and connecting some specific device.

Physical sockets

Electrical sockets

A CPU socket is a physical and electrical specification of how to connect a CPU to a motherboard.

In electronics, a socket is also used as a synonym for a jack.

An electrical socket is a synonym of electrical outlet: an electrical device connected to a power source onto which another device can be plugged or screwed in. Typical examples are wall sockets and light bulb sockets. See Domestic AC power plugs & sockets.

Biological sockets

• Eye sockets or orbits are regions in the skull where the eyes are positioned.
• When a tooth is pulled, if the hole becomes painful as a result of the blood not clotting so as to keep it moist until it heals, the opening is referred to as a dry socket.

Computer sockets

In the world of computers, there are two types of sockets- Internet sockets, and IPC sockets.

A socket can be used in computer networking to form one end of a bi-directional communication link between two programs, likely over a network, though exceptions like the X Window System exist.

Sockets can also be used for IPC, without IP addresses or any other staples of TCP/IP.

Internet sockets

In RFC documents relating to TCP or UDP, a socket on a certain host is defined as the combination of an IP address, a protocol, and a port number.

The BSD operating system introduced network sockets in 1983: see the Berkeley sockets API. Each socket gets bound to a given port, which lets the transport layer protocol (typically UDP or TCP) identify which application to send the data to.

Unix domain sockets, IPC sockets

Another type of socket is used by POSIX compliant systems, and are called Unix domain sockets (the correct standard POSIX term is POSIX Local IPC Sockets). Their primary function is as a means for inter-process communication and are therefore also called IPC sockets. These connections are from the local computer to itself, not actually a connection transmitted over a physical network.