Do you have to have a modem and a router?

A wireless router provides a wireless network, but does not provide internet connectivity by itself, unless it is a combination router/modem, such as a Motorola Surfboard. A typical home wireless router will not have this functionality included, so a cable modem is often required to access a cable provider's Internet service. Buying a device that includes both wireless routing and cable modem features will allow the network to access the Internet without a dedicated cable modem, while all others will require a cable modem separately. In either case, a device that provides the features of a cable modem is required for cable Internet.