Good question - one many people don't ask until their hosting account is suspended for exceeding their bandwidth.
Bandwidth is the amount of "traffic space" your website uses -- and it's usually measured per month by most hosting companies.
Popular e-commerce sites need to be careful of exceeding their bandwidth as do businesses that get a lot of high-profile media coverage. When people visit your website, when they access or view the graphics and information on your site, it takes up space - that space is called bandwidth.
A good rule of thumb is to ask your hosting company how they handle excess bandwidth usage. Some hosting companies will automatically bump you up to the next plan level while others will disable your account altogether - not good.
Ask your hosting company to recommend bandwidth levels based on existing traffic and then if you need to adjust it downward at the end of the month, you'll have that option.
Lena West is the CEO and Chief Strategist of xynoMedia Technology, a New York-based firm that helps high-growth companies leverage the power of social media, blogs, podcasts and online communities.