SEO stands for Search Engine Optimisation.  It is the art of telling the search engines what a page on a website is about and ensuring that it appears above those of your competitors.

The optimisation of a page means that when the spiders from a search engine visit a page they are quite clear that the page in question relates to this specific topic and in particular this keyword or phrase.

SEO also encourages the search engines to give that page the highest possible score for the targeted keyword or phrase, while making sure that they do not get a penalty for incorrect use of the different elements involved.

It is SEO that helps your site rise in the search engines.