A switch is a networking device, usually featuring multiple input and output ports. Switches are designed to take incoming traffic, examine it and send it to the correct destination. On Ethernet networks, switches use Media Access Control addresses to identify where data needs to be sent. Each device connected to the switch has a unique MAC address, which it gives to the switch when the network connection is made. As such, if the switch receives traffic for that address, it knows which interface to send that traffic to.