SEO is the practice of optimizing a website’s pages to ensure that they are search engine friendly and that they target their intended audience. Each of the major search engines (Google, Yahoo!, MSN, and Ask) send out spiders or crawlers. These are programs that come to your website and collect all the information about each web page and take it back to the search engine’s database. The search engine stores the information about the pages it collects and then presents it when a query from a search matches what your page is about. Each search engine applies its own algorithms to determine a page’s relevence to the searcher’s query, and returns a set of results.

Be careful with SEO firms!

“SEO is an abbreviation for “search engine optimizer.” Many SEOs provide useful services for website owners, from writing copy to giving advice on site architecture and helping to find relevant directories to which a site can be submitted. However, a few unethical SEOs have given the industry a black eye through their overly aggressive marketing efforts and their attempts to unfairly manipulate search engine results.” From Google

No one can guarantee a #1 ranking on Google

“Beware of SEOs that claim to guarantee rankings, allege a “special relationship” with Google, or advertise a “priority submit” to Google. There is no priority submit for Google. In fact, the only way to submit a site to Google directly is through our Add URL page or through the Google Sitemaps program, and you can do this yourself at no cost whatsoever.” From Google

For a more in depth description of how Google ranks a website and what to do to improve your ranking please visit Google Webmaster Resources