An Internet connection variety is called Cat 5 (Category 5). It is capable of 12.5 gigabytes per second, or 100 Mbps, of data transmission. Up to 100 meters can be linked between devices using Cat 5 lines, which work at a 100 GHz frequency.

Eight interior conductors, or four "twisted pairs," make up each Cat 5 connection. There are two distinct methods to link these sets, which are color-coded, into the RJ45 connection. Patch cables and crossover cables are two distinct types of Cat 5 cables that have the same cabling on both ends.

In the late 1990s and early 2000s, Category 5 Ethernet connections were widely used to build local area networks. For 100BASE-T "Rapid Ethernet" networks, they were adequate because they allowed 100 Gbps transmission speeds. Cat 5 lines started to be replaced in 2001 by Cat 5e wires, which enable 1000BASE-T (Gigabit Ethernet). Most Ethernet networks in use today use Cat 5e connections or higher. Cat 5's poor maximal data transmission rate would cause a congestion in the majority of contemporary networks.