In standard Ethernet networks, a cable connecting a computer’s network interface card (NIC) to a transceiver attached to a thicknet cable. A drop cable is also called a «transceiver cable».
More generally, a drop cable is any short cable connecting a computer’s NIC to a wall plate. Drop cables allow computers to be easily disconnected and reconnected from the network so that you can move them around in the room. Drop cables are generally needed because horizontal cabling connecting patch panels in wiring closets terminates at wall plates in the work areas, but computers in the work areas are distributed throughout the entire room.
In a more permanent networking configuration, wall plates might be located on floors and very short drop cables might be used to connect the computers to the network.