-They are provided as a form of IPC.
-They do not form true protocol suite in sense of communication protocols.
-They are useful to transfer data across processes in the same host.
-The advantage over othre IPC is that it has same API as other comm protocols .
-There are two different protocols - i) Unix Domain Stream Protocol - Reliable, Connection-oriented, Byte Stream Protocol. ii) Unix Domain Datagram Protocol - Unreliable, connectionless, Datagram Protocol .