The Google Webmaster tools page is, in short, a place for you to log in and submit sitemaps for your websites, thus informing Google of changes and updates to your sites, which in turn means these pages should get indexed quicker.
A Sitemap is an XML file that lists the URLs for a site. It allows webmasters to include additional information about each URL: when it was last updated, how often it changes, and how important it is in relation to other URLs in the site. This allows search engines to crawl the site more intelligently.
Sitemaps supplement and do not replace the existing crawl-based mechanisms that search engines already use to discover URLs. By submitting Sitemaps to a search engine a webmaster is only helping that engine’s crawlers to do a better job of crawling their site(s). Using this protocol does not guarantee that your web pages will be included in search indexes nor does it influence the way that pages are ranked by a search engine.
