(1) A network infrastructure component to which multiple nodes attach. Unlike a hub, a switch typically has internal bandwidth that is a multiple of link bandwidth and the ability to rapidly switch a node connection from one to another. A typical switch can accommodate several simultaneous full-link bandwidth transmissions between different pairs of nodes.
(2) A device that provides connections between telephone lines and trunks.
(3) A half-duplex or full-duplex device that detects which devices are attached at each port and passes only frames addressed to those devices on that port. A switch has a small collision domain.