Crossover cable

A crossover cable is a cable that maps all output signals on one electrical connector to the input signals on the other connector, allowing two electronic devices to perform full-duplex communication. Most commonly, the term refers to the Ethernet crossover cable, but other cables follow the same principle. It also allows devices to communicate without a switch, hub, or router. Cross-Over cables are used to connect two computers directly through NICs without the use of a Hub or Switch or to uplink two or more hubs, switches or routers.

en.wikipedia.org/wiki/Crossover_cable