The search engines use complex algorithms to determine your rankings for various keywords. In the past few years Google, Yahoo and MSN which provide a vast majority of the search results are relying more on the content (selectable text) and inbound links (links from other sites to your site) to determine the popularity and relevance of your site. By improving those areas you are likely to improve your rankings. The search engines regularly tweak their algorithms to attempt to provide better results to searchers. Your ranking may change based on these updates. Your ranking will also likely change for better or for worse when you make alterations to your web site.
