What is an RJ45? Come to think of it, the better question would be to ask what use it has in the technological world. As much as the cable connector sounds like a complex abbreviation used for military purposes, it is in fact put simply an eight wire connector that connects computers together. It has many purposes which include networking the computers together so they can communicate better with each other and transfer information quickly.

The RJ45 looks much like a telephone connector; however, it is so versatile that it can be connected to almost anything with intention of communication and networking. The more familiar type of registered jack is the RJ11, which is seen mainly in North America connecting phone lines in homes and offices. These look very similar to an RJ45; however, the latter is used mainly for connecting computers on a local area network (LAN) and Ethernet rather than for simple telephone lines.

These jacks were introduced and produced by the Bell System company, during the 1970's. These were designed to take over the bulkier connectors commonly used in military bases. The jacks were made with a USOC (Universal Services Ordering Code), which is a specific type of connector and wiring standard of that time. This was used primarily for connection of telephones and usage through the FCC wiring standards. The FCC then decided to hand over the registered jack production to a private company namely the Administrative Council for Terminal Attachment (ACTA).

These days the registered jack has seen many changes, improvements and diversions from its original usage as a telephone connector. Some of the jacks have suffixes distinguishes them from their type and how they are connected. For instance C would indicate a surface mount; W would indicate a wall mounted jack; S as a single line registered jack; M as a multi-line and X as a complex jack. Each one is also sub-divided for its connection type and its physical appearance.

The RJ45 is also known as an 8P8C connector, which literally means eight position eight contacts. In laymen's term this determines the number of positions with the number of positions in a contact connector. There are other types of connectors available such as the 8P6C or the 6P6C. There are two types of 8P8C plugs; these are Western Electric/Stewart Stamping (WE/SS) and Tyco/AMP. Both of these look very similar to each other; however the latter have smaller spacing than the former. A WE/SS is more common and both cannot be interchanged.

In terms of the RJ45, this uses the same type of connection as the 8P8C, which means it has a much wide plug surface and uses a different type of 8P than the standard 8P8C. These are great for connecting to the LAN and can be used to an advantage of the home user, especially for those keen on LAN games (where each player has their PCs connected to each and play against each other).