A standard modems job is to convert data from its digital form to analog form, which are then transferred over a phone line and reverse done while receiving data from the telephone line to your computer. By doing both modulating and demodulating the data signals, it is called to be a Modem.
A broadband modem is quite different from those of dial-up modems. You need it when you take a broadband service for the first time. Usually providers offer modem along with you package or may ask you to have a modem at extra cost. Anyhow, getting the modem from your broadband provider should be safe being supported by your provider and should work fine with the setup.
In case your provider does not offer a modem then you can get a modem of your choice. There are wide types of modem out there and it is good before to check with your provider for a suitable modem. If you are in preparation to set up a network to share your internet connection then you require a router modem.
Broadband modems are still limited to utilize analog/digital conversion. But most recent advanced modems are capable of modulating/demodulating hundreds of channels simultaneously. Also many broadband...