In computer networking, a repeater is a device which takes an incoming signal and then repeats it. If it is a digital repeater it will regenerate the signal, which will clean up any distortions. If it is an analog repeater it will amplifly the signal, including any distortion. Repeaters must follow the 5-4-3 rule, which states that you can only have 5 segments of cable connected by 4 repeaters, and only 3 of the segments can have a host. Repeaters have pretty much been made obsolete by hubs, which are basically multiport repeaters. Hubs, in turn, have mostly been replaced by switches. Because a repeater is a transceiver, it can take an electrical signal and convert it to an optical or radio signal.