Crossover Cable is a #Twisted Pair Cable where the pins 1 and 3, and pins 2 and 6 are swapped on one end of the cable. It is used to connect two Network Devices# of the same kind.
Note: Router and Personal Computer (PC) are considered to be the same kind of end device since they both could operate at Network Layer#.
Router consists of two types of interfaces: LAN interfaces and WAN interfaces. LAN interfaces could be used to connect Router to the LAN which is typically connected with an RJ-45 jack (Unshielded Twisted Pair Cable (UTP)). For connecting Router to Switch, we use a Straight-Through Cable. In the case of Router to Router, we use a Crossover Cable. For PC to Router, we will use Roll-Over Cable. LAN interface could serve Ethernet# and Fast Ethernet.