Once you get into building sites, you will be confronted with the disconcerting truth that no one knows about your site. And isn’t that why you started your site in the first place? It’s a hard reality that any web site owner has to face. One of the ways that you can get people coming is to utilize sitemaps.
So, what are sitemaps? Sitemaps are just sets of links that help people or spiders to see the site more clearly. Now, there are, as I already alluded to, two main types of sitemaps - those that are geared toward people and those geared toward search engines. The type for people are usually done in html and make it easy to see how the site is structured. It’s a visual map. The other kind is usually an xml file. It’s not pretty looking to humans typically, but search engine spiders love them. This allows them to quickly update their listing of what is on your website. Then you can use things like Google Webmaster Tools or Yahoo Site Explorer to submit it.
search engines
sitemaps spiders xml file 
