While the term has fallen out of common usage, the Internet used to be called the Information Superhighway, and that neologism is a good starting point for understanding bandwidth, and how it effects your web shop and business.

Bandwidth is measured in bytes per second, usually in kilobytes per second. Using the Information Superhighway analogy, think of the network connection that leads customers to your web site as being the road that leads them to a physical store. If you've got a one-track rutted trail that goes through a swamp, you're going to have a hard time getting customers to your site at all. That one-track dirt road through the swamp is analogous to most "Unlimited Bandwidth" hosting sites.

The place where the Internet Superhighway analogy breaks down is that all the network connections are toll roads. And the toll gates keep track of how much traffic goes over the road, and will either shut the gate down (most so-called "Unlimited Bandwidth" hosting sites), or they'll just send you a large (and unexpected) bill at the end of the month.

You should be working with your hosting provider to get tools that monitor how much bandwidth you actually use. They have statistics packages that can tell you what parts of your web site are getting the hits, and where from, and what parts of the web site are using the most bandwidth to load.

The common causes for bandwidth explosions on your web site are large files that get accessed a LOT, like video clips, Flash animations and client downloads for things like online games. Secondary causes are, believe it or not, "squeeze page" type layouts, that condense a lot of content into a small area, particularly if they refer to off-site graphics or data stores. If you think of each graphic as being a parcel, and the gate keeper on the toll road measuring traffic by the total weight of the parcels on the truck, you'll get a good clue as to what's eating your bandwidth all over the place.

Other causes of bandwidth usage spikes are so-called "bandwidth thieves", who link to your materials directly. There are server settings you can enable that will block calls to your graphics from other domains, but they aren't turned on by default.

When setting up a web based business, do take the time to consider bandwidth as one of your on-going company expenses, and work out a budget for the bandwidth you'll actually use, and know what it's going to cost to get more. The good news is that Moore's Law applies to networking technology as well – common predictions that the Internet will run out of bandwidth have been made since the Web was started by Tim Berners-Lee, and have proven to be as laughable as Bill Gates saying that 640K of RAM was enough for anyone.