Sockets

A socket is a file descriptor connected to the network
What "the network" is depends on the protocol family

Sockets in the AF_UNIX family are filesystem-based
They are not the same as localhost TCP/IP

AF_UNIX sockets, like AF_INET, offer two main socket types
SOCK_STREAM
SOCK_DGRAM (e.g.: syslog)

Several advantages over pipe/FIFO
Communication between unrelated processes
One entry point for several concurrent unmixed clients
Support for client authentication
Communication can be local or remote, with minimal changes