Definition – What does RJ45 mean?
RJ45 is a type of connector that is used for Ethernet networking. It looks similar to the telephone jack but is slightly bigger. Since Ethernet wires have an RJ45 connector on both ends, sometimes Ethernet cables are also called RJ45 cables. The RJ stands for registered jack since it is a standardized networking interface and the 45 refers to the number of the network standard.
Glossary Web explains RJ45
Each RJ45 connector has eight pins that mean the cable contains eight wires. If you look carefully at the end of the cable, you can actually see the eight wires that each are a different color. Four of them are solid colors, and the other four are striped. All the RJ45 cables can be wired in two different ways such as T-568A, and the other is T-568B.
The T-568B wiring scheme most common, though most of the devices support the T-568A wiring scheme as well. Some network applications require a crossover Ethernet cable that has a T-568A connector on one end and T-568B connector on the other. Typically, this kind of cable is used for direct PC-to-PC connections when there is no hub, router, or switch available.