If you already have a broadband connection (such as Cable, DSL, etc.), or just signed up for one, your service provider will make all kinds of promises about how fast the connection will be. Then after you have it installed there is no way to truely tell if you're really getting the bandwidth you're paying for.
If you want to validate the speed of your Internet connection, you will need to use a web site that can measure its bandwidth. There are several of these sites available on the Internet that can measure how fast your Internet connection is, but some seem better then others.
One of these sites that I like is from a company called Speakeasy, they have an easy to use and easy to understand connection speed test. All you have to do is select a server that is close to where you live, and watch your computer's display.
Note: The results of these tests can be affected by several factors, such as other people sharing your connection or processing loads on the Speakeasy servers.