Routers help add more devices to your internet connection. Some offer WiFi access, some hard-wired, and other both types of connections. Depending upon what you need to connect will help you know what product to buy.
T1-> T3 network services
|DS# broadband speeds
Voice Channels are possible
OC# network broadband services
Did you know that renting a modem from your cable company each month costs you $10+ a month? If you buy your own cable modem, that fee goes away. So for a very high end cable modem like this one, you can buy for about $200, you break even in less than 2 years! Be sure to check out the Pre-Purchase checks to make sure you get a compatable device.
Learn about what is an Internet Service Provider (ISP), they are a information junkies necessity! This is the important connection between you and the internet.