RJ45 is a kind of information socket (communication terminal) connector in wiring system. It is made of a plug (connector, crystal head) and a socket (module).The plug has 8 grooves and 8 contacts.

RJ is the Registered Jack for short, which means “registered jack”. In the FCC (Federal Communications Commission Standards and Regulations), RJ is an interface that describes a public telecommunication network, and the RJ45 of computer network is a normal call for a standard 8-bit modular interface.