RJ45 is a commonly used connector type for Ethernet network. Ethernet cables are also sometimes called RJ45 cables because Ethernet cables have an RJ45 connector on each end.

The "RJ" in RJ45 stands for "registered jack" as it is a standardized network interface. "45" simply refers to the number of the interface standard. Each RJ45 connector has eight pins. This means that the RJ45 cable contains eight separate wires. If you look closely at the end of an Ethernet cable, you can actually see eight wires, each a different color. Four of them are solid color and the other four are striped.

RJ45 cables can be wired in two different ways. These are T-568A and the other is T-568B.

The T-568B is the most common, but many devices also support the T-568A wiring scheme. Some network applications require a crossover Ethernet cable with a T-568A connector on one end and a T-568B connector on the other. This type of cable is often used for direct computer-to-computer connections when there is no router, hub, or switch.