There are 2 types of bandwidth.

1st - If you want a fast connection, you will need to move more data faster. This will take more bandwidth to accomplish. Think of it as sitting on the side of the Mississippi River trying to drink water with a coffee straw. You won't get much until you get a bigger straw. Bandwidth is the straw.

2nd - Bandwidth can be measured in the amount of data and how fast your website sends it to users. This is usually measured in dollars per GB. Halo could explain it better. Some people use it more wisely then others.