Just as most cell-phone packages have an allotted number of hours or minutes, your web host will probably have some bandwidth limits attached to it. So, in this context, bandwidth is a measurement of how much information has been downloaded from the server hosting your site to the visitor’s computer.

Every picture, background image, navigation button, and HTML page on your website is a certain number of kilobytes in size. And every time someone visits your site, all of your images and files need to be transferred over the Internet and displayed on the visitor’s computer screen. That’s bandwidth.

Most people don’t need to worry about extra bandwidth costs because they do use a lot of it. Typically, adult sites, file-sharing sites, Oprah, or Amazon.com are the kinds of sites that need to be concerned with bandwidth and traffic volumes.