Broadband is a term for various techniques making connection to the Internet possible. These techniques include among others: fiber, ADSL and mobile broadband.
Fiber stands for a network consisting of fiber cables pulled underground up to different objects including houses. This a future-proof type of broadband enabling high transmission capacity.
Broadband via ADSL provides connection to the Internet over regular telephone lines by means of digital modems.
Mobile broadband allows Internet connection with the help of a wireless network card, a modem or a mobile telephone. That means with a mobile broadband you are not bound to a certain place.