An RJ45 plug is used for connecting to Cat5, Cat5e and Cat6 data cables. As shown in the RJ45 wiring diagrams below the three commonly used Pinout configurations for connecting RJ45 plugs are T-568A, T-568B and Crossover.
The most commonly used RJ45 Pinout connection is T-568B, this is generally used for standard data connections such as from your internet router to your PC, structured data cabling, a standard patch cable, CCTV cameras and Ethernet cables.
Standard internet connections generally follow the T-568B configuration.