An RJ-45 connector (RJ45) is an internet cable connector which is compatible with registered jacks known as RJ-45 ends. RJ45 ports and jacks are used most commonly with ethernet networks and cables. The most commonly use ethernet cables today are plugged into RJ45 jacks on routers, computers, and other net capable equipment. The RJ45 is the port on these devices which receive the jack that is on the ends of an ethernet cable.
An RJ45 ethernet connector features 8 pins and the wires strands of a cable interface with these. Each port has 8 locations or ‘positions’ which are spaced roughly 1mm apart from each other.
Older dial-up modems made use of a type of ports which were called ‘RJ45s.’ These used only 2 contacts rather than 8, but the RJ45 and RJ45s connectors were so similar in appearance that many people confused the two until the newer connectors more or less completely replaced the older ones.
Possibly the most common problem with RJ45 jacks and ports is they will occasionally make a poor fit which results in a loose connection. Users will frequently have to use tape to hold the jack in place. Most RJ45 jacks come with a tab which is nearly identical to those on the jacks for landline telephones of the 1980s and 90s. These tabs lock into the port with an audible click that lets the user know a sound connection has been established. These tabs tend to be a bit fragile and can be broken if snagged on clothing or if the jack is pulled from the port without depressing it properly.