When we talk about RJ45 ("Registered Jack" 45) we refer to a telecommunications network interface for wired connection of voice and data equipment.

This connector has 8 pins or connections and may have a specific category depending on the data transfer speed and bandwidth (category 5e, 6, etc.)

The common application is their use in Ethernet network cables under TIA/EIA-568-B standard that defines the arrangement of pins (pinout), but can also be used for other applications.

- Direct pin diagram:

EIA-568A
Pin No.1: WHITE-GREEN
Pin No.2: GREEN
Pin No.3: WHITE-ORANGE
Pin No.4: BLUE
Pin No.5: WHITE-BLUE
Pin No.6: ORANGE
Pin No.7: WHITE-BROWN
Pin No.8: BROWN

EIA-568B
Pin No.1: WHITE-ORANGE
Pin No.2: ORANGE
Pin No.3: WHITE-GREEN
Pin No.4: BLUE
Pin No.5: WHITE-BLUE
Pin No.6: GREEN
Pin No.7: WHITE-BROWN
Pin No.8: BROWN

- Schematic of crossed pins:

The crossover cable has one end with EIA-568A scheme and the other one with EIA-568B.

A connector IDC (insulation-displacement connector) connector IDT (insulation-displacement technology/termination) or insulation displacement connector is an electrical connector designed to be connected to a driver (or drivers) of an insulated wire through a connection process by selective isolation through one or more sharp blades, avoiding the need to strip the cable cover before connecting.The ribbon cable (also known as strip wire or ribbon cable) is designed for use in multi-pin IDC connectors so that the IDC connections can do at once, saving time in applications where many connections are required. These connectors are not designed to be reusable, but can be used again if care is taken to remove the cable.