An Ethernet cable is one of the most popular forms of network cables used on wired networks for the purpose of transmitting network information. The commonly seen Ethernet cables are twisted pair cables, which can be divided into two categories: shielded twisted pairs (STP) and unshielded twisted pairs (UTP). In general, the most commonly used are unshielded twisted pairs which consist of four thin copper wires with each pair of copper wires twisted together, each copper wire wrapped in colored plastic insulating layer, and wrapped with a layer of plastic coat as a whole. Unshielded twisted pairs adopt RJ-45 interfaces, so they are also called RJ-45 cables. Normally, UTPs can be classified into 5 types: Cat5, Cat5e, Cat6, Cat6a, and Cat7. This post will explain the classification of UTPs and differences between them in detail.