All of the web hosting plans offer certain amounts of data transfer or bandwidth. Why ?
Data transfer, sometimes called “bandwidth”, refers to the amount of data that is used when visitors view your web site for a month. When visitors browse your web site, they are technically requesting and retrieving files from the server. If you have a web page that consists of an HTML file and an image file that are 10kb each, then the amount of data transfer that is used when a single visitor views that web page is 20kb. Both your web site and FTP data transfer are measured.