Is your school blocking some sites? Is Facebook blocked, and you'd like to access it? You'd like to browse to Facebook, and the school has it blocked? Then read on.
Unblockers are like a gateway that work between the computer you're on and the site you're visiting. The unblocker goes to the site you want instead of you, downloads the page, and sends it off to you. So the site you want to be on only sees the unblocker's IP. So actually you are surfing websites in an indirect way. Internet filters only think you are visiting the unblocker, not the destination site.
An alternative method of unblocking Facebook at school is by setting up your own unblocker tool. This is more advanced than just using an unblocker but it pays off because if they block it, you can make another. How to do this is too much effort to explain here, if you search for "How to make your own proxy" you should find instructions. You can also earn money from your unblocker if you put ads on it.
Some other ways to unblock Facebook include by using translator sites, for example Google Translate or Babelfish. Also try Google's cached version of the site. Although, you can't to log in using these methods, so it's still best to use an unblocker for Facebook, though these tips are good for many other sites.