RJ45 being a standard type of connector for networking cables is widely used in Local Area and Wide Area Networking.
RJ45 stands for Registered Jack 45. RJ45 broadly refers to RJ45 connector, RJ45 cable and RJ45 port. A RJ45 Connector is an eight-wire connector used to connect computers in a Local Area Network (LAN) via Ethernets. RJ45 originally used in telephone cables was a 8P2C (8 position 2 conductor) modular connector whose pin 5 connects to tip and pin 4 connects to the ring. Computer RJ45 is an 8P8C (8 position 8 conductor) connector with all conductors present. Today RJ45 is used almost exclusively to refer to Ethernet type computer connectors. In general all 8P8C connectors are also referred to as RJ45 connectors.
RJ45 cables fall into three main types namely a) straight-through, b) crossover and c) rolled. The colored wires are in the same sequence at both ends of the straight-through cable. In crossover cable the first (far left) and the second colored wires at one end of the cable are the third and fourth colored wires at the other end of the cable while the third and fourth colored wires at one end are the first and second in the other end. The colored wires at one end of the cable are in the reverse sequence of the colored wires at the other end of the cable in the rolled type. The most common RJ45 connector uses four of the 8P8C wires for Ethernet communications. Pins 1 and 2 are the transmit pair while pins 3 and 6 are the receive pair.
The Ethernet port resembles a wider looking regular telephone jack. The cable and the RJ45 data port support communication at speeds up to 1 Giga bits per second (GBps) (one thousand million bits per second). In addition to Ethernet, RJ45 cable is used for WAN connections. Faster serial communications also employ modular 8P8C. Six of the eight connectors are used in certain Integrated Services Digital Network. Augmented RJ45 (referred as ARJ45) to be used with a modified RJ45 port has been designed for high speed communications (10GBps).
The benefits of using RJ45 / Ethernet connections are the high speed data throughput reaching up to Gigabit/s levels over long distances. The other competing LAN standards like Token ring, Token Bus, etc., suffer degradation as when new nodes come into LAN. With a locking boot RJ45 plug connector remains free of any inadvertent disconnection taking place.