An Ethernet crossover cable is a cable that can be used to create a very simple computer network. To create a computer network, one must join at least two computers together for sharing program files and data. Sometimes, computer networks are extremely complex, involving many computers, as well as routers and hubs. Each of these computers interacts and shares data with the others.

While this may be necessary for large organizations, sometimes there is a need for only a very small network of two or three computers. These Local Area Networks, or LANS, have been designed to communicate via Ethernet cables since the late years of the 20th century. Crossover cables are very similar to standard Ethernet cables. They are more effective, however, because they allow the operator to join two computers without requiring the presence of a hub or router, and permit each computer to communicate with the other. This simple design, which differs from a standard cable only in that the crossed wires allows the two computers to both send and receive information from each other, is very effective.

Another reason for using a crossover cable rather than a more complicated device such as a modem or router is that, in order to successfully connect two computers using one of these devices, one needs a second crossover cable to allow the computers to communicate. This is because most hubs, routers, and other devices contain an internal crossover wiring format. Using an Ethernet cable permits one computer that is connected to a modem to obtain internet access. If, however, multiple computers require access, the user should add a hub. This device is joined to a router by using a crossover cable. In turn, each computer is networked to the hub with a standard cable.

Through the use of a crossover cable, multiple computers can communicate back and forth with each other directly or through the use of additional tools, including modems, hubs, or routers. Furthermore, users who are joining only two computers do not need to pay the additional cost or spend extra time and effort adding a hub to their LAN. These cables can be purchased economically through the internet or at stores that sell computer-related merchandise.