RJ45 is a connector commonly used in Ethernet networks. It looks like a telephone jack, but it is slightly wider. Because there is an RJ45 connector at both ends of the Ethernet cable, the Ethernet cable is sometimes called an RJ45 cable.
The "RJ" in RJ45 means "registered jack" because it is a standardized network interface. "45" only refers to the number of the interface standard. Each RJ45 connector has eight pins, which means that an RJ45 cable contains eight individual wires. If you look closely at the end of an Ethernet cable, you can see eight wires, each of which has a different color. Four of them are solid colors, and the other four are striped.
