RJ45

RJ45 is used to permanently set the LAN (Local Area Network) cable insertion clamper. This type of connector was originally developed for telephone communications but it is now used in a range of applications.  In other words, it is used when networking on computers. RJ-45 is a short form of Registered Jack-45.  

For example, look at the RJ45 in the below picture. 

Fig: RJ45 and Network Cable