Search Engine Optimisation
SEO is a big buzz word at the moment. SEO or Search Engine Optimisation (Optimization if you're American) in a nut shell, is simply making sure that your website is "Optimised" so when a search engine visits your website and assesses it against their criteria and against your competitors websites. Many things can affect your score or page rank such content, html errors (the code that is used to make the website), the speed your website loads, even where it is located. SEO isn't just about your website. It is how your website interacts with the rest of the internet.
You can have the best looking website, but if it isn't optimised, then it isn't being seen