Every time a visitor visits your web page, the server they are accessing sends them the data they need in order to view that particular web page. This includes all images, scripts, and includes that the server needs to send to give you the complete page. The way web hosting companies measure the data that your server is sending to visitors, is called bandwidth. Bandwidth is measured in bytes, but you will see it normally given quantities of megabytes and gigabytes. A megabyte is 1,024 kilobytes (which is 1,024 bytes) and a gigabyte is 1,024 megabytes.

The reason you should be concerned about bandwidth is that it is the way web hosting companies limit the amount of resources your server can use. The web hosting company usually will let you use as much bandwidth as you want at any point, up to a predetermined limit. When you reach this limit, your web page will more than likely be shut down, or your web hosting company will try to charge you for using more bandwidth than you were supposed to.

Bandwidth is very important if you want to keep visitors coming and reading your webpage. Each time they do this, however, you will be using your allotted bandwidth. So keep an eye on how much bandwidth you are using each month, and possibly upgrade to bigger plan if you need to.