an XML sitemap is used to notify search engine crawlers about all the pages in your website. It is written in a format that they understand so that they can see where all your pages are. See this for more information: https://www.google.com/webmasters/tools/docs/en/protocol.html Once you have created your XML sitemap you can add the location of where it is situated on your site on Google's Webmaster tools. You can use the same location on the Yahoo site explorer although it is named "feed" for Yahoo. On the Google Webmasters tool and Yahoo site explorer is a section where you can see how many pages are indexed from your XML sitemap. Hope this info helps