XML Sitemaps are an easy way for webmasters to tell search engines about pages on their site that may be crawled by their robots. A typical XML Sitemap file lists each URL, together with information about when it was last updated, how often it normally changes, and how important it is, relative to other pages in the site). This helps search engines to more intelligently crawl your site. In November 2006, Google, Yahoo! and MSN joined forces to support a new industry standard for sitemaps: Sitemaps 0.90. As long as webmasters follow the protocol, they can ensure their sites are fully and consistently indexed across all the major search engines (a real step forward).