A modem can convert the incoming signal from the cable lines coming into your home into a format that a router, and your connected devices, can use. In fact, the word modem is short for modulation ...

and a router, which forwards traffic to the modem and distributes responses to the requesting machines. If the cable modem/router has Wi-Fi, it is a "wireless gateway" (see cable/DSL gateway).

The two major components in a small computer network are a modem and wireless router. The modem is wired to the Internet via the cable company's coaxial cable, the telephone company's DSL phone ...