A switch is a piece of network hardware that extends the functionality of a router. In networking terms a switch is a layer 2 multiport bridging device. It also extends the functionality of a router. In networking terms, a switch is a layer 2 multiport bridging device. Some switches have configuration options themselves called Smart Switches. Others are just plug-and-play. Additionally, some switches can provide an electrical current to power devices that they connect to. This utilizes a standard called Power over Ethernet (PoE).