To get the best deals, you usually have to sign up for a minimum contract - such as 12 or 18-months. Though, if you need to cancel before it's up, you can be hit with hefty penalty charges, particularly if you've still got a long time to go. If you're planning to move home soon, live in student accommodation or want the freedom to leave at any time, you can sign up to broadband deals with no contract which, although more expensive, can be cheaper than paying to escape a long contract.
I'm moving home soon, is it worth getting a no contract deal?
It depends on the provider, and sometimes the deal you sign up to. Before signing up to a long contract, check if it's 'portable', meaning you can take it with you when you move. Some providers will let you do this, but it can often be on a case by case basis and whether the company can supply your new home, as broadband is postcode dependent.