1. Understanding sockets
The English literal of the socket is "hole" or "socket". As the BSD UNIX process communication mechanism, take the latter one meaning. Often also referred to as a "socket," which describes IP addresses and ports, is a handle to a communication chain that can be used to communicate between different virtual machines or different computers. Hosts on the internet typically run multiple service software, while providing several services. Each service opens a socket and binds to a port, and the different ports correspond to different services. The socket is like a porous socket, as its English intended. A host is like a room full of various sockets, each outlet has a number, some sockets provide 220 vac, some provide 110 volts AC, some provide cable TV programs. Customer software plug into different numbered sockets, you can get different services. (from 36,000 subjects above)
The simple point is that the socket is a technology that allows us to walk between the client and the server side.
2, understanding Socket Basic Communication model (using TCP Transport protocol example)
Understanding Socket Basics