What is a Sitemap?
There are actually two different kinds of sitemaps. The first kind of sitemaps is a web page that lists all the pages on your web site. This can be useful for their visitors if they are trying to find a specific page on your website.
The other kind of sitemap, is an XML Sitemap or Sitemap with a capital S. This type of sitemap is used to give Google information about your web site.
A Sitemap is also a list of pages on your website, but it is not a list for your visitors. You must first create a Sitemap and then submit it to Google. This helps to make sure that Google knows which pages to spider (look at) and index on your website.
XML Sitemaps can also provide additional information about you web pages such as how often you update them, when the page was modified, and how the relative importance of the page.
For more information visit Google’s Help Page about Sitemaps.