Ethernet is a high-speed networking system that connects computers, servers, and printers to share data. It was invented in 1973 by Bob Metcalfe of the Xerox Palo Alto Research Center (PARC). Today it is used in nearly every wired network.
Ethernet cables use copper wires formed into twisted pairs within the outer jacket. They are available in many shapes, including slim, ultra-slim, flat, solid core, and armored cable. The wire gauge and construction determine the cable category, which drives the maximum data rate and bandwidth.
Category 1 (Cat1) cable is a single unshielded twisted pair used for telephone lines with a data rate of 1 Mbps and bandwidth of 400 kHz. Cat2 is an improvement to 4 Mbps and 4 MHz. Cat3 uses four twisted pairs supporting 10BaseT Ethernet with a 10 Mbps data rate and 16 MHz bandwidth. Cat4 offers a slight speed improvement to 16 Mbps, data rate, and 20 MHz bandwidth. Cat5 achieves 100 Mbps and 100 MHz bandwidth. Cat5e uses increased twists in the four pairs to achieve a 1 Gbps data rate.
Cat6 uses shielding and a physical separator between the pairs to reduce crosstalk. The data rate is 1 Gbps and 250 MHz bandwidth. Cat6a increases the data rate to 10 Gbps and bandwidth to 500 MHz. Cat7 and Cat7a support 10 Gbps data rates and 1 GHz bandwidth but have not been endorsed by IEEE or TIA/EIA. Instead, Cat8.1 offers 25 Gbps data rates, and Cat8.2 has 40 Gbps. The bandwidth is 2 GHz. It does this with foil shielding and heavier gauge wire.
Connectors are most typically RJ45 with eight pins. But there are also M12 connectors that are threaded to provide a waterproof connection.