In order to get enable WiFi in your home network, you will need to pair your cable modem with a router. The router powers WiFi and allows you to connect multiple devices to your network wirelessly, where as the modem is limited to a wired connection to a single device.
Do I need both a cable modem and wireless router?
Routers and modems have traditionally been two separate devices that worked together to form your home network. However, with today's technology, you don't need a separate modem and separate router necessarily, as new combination modem and router units merge the two devices' functions into one powerful gadget.
Is a router necessary?
You do not need to have a router to use Wi-Fi as long as you're not trying to share an Internet connection. The common consumer Wi-Fi router is actually a combination device that includes a network switch, a network router and a Wi-Fi access point.
Can a modem be used as a router?
It's simple. You will need a wifi router if you don't opt to change your existing modem to a modem+router. If you choose to buy a router to achieve this capability, just configure your current modem to bridge mode. Then connect the output LAN of your modem to your router's IN.