In a recent Webmaster Central blog post released on the 16th October, Google have said that for ‘best practice’, webmasters should submit both XML Sitemaps and RSS / Atom Feeds for search engines to index their sites.
An XML Sitemap is a complete list of all of the pages on your website and where they can be found. It explains to search engines the organisation of all of your content so that the search engine can index your site and lead visitors along the right path. It also contains meta data, such as the date it was last updated and also a suggested priority of indexing over other pages on the site.
An RSS or Atom Feed is much the same (they both use the same XML language), but it sends only updated information, not a full map.
While most search engine bots, such as Googlebot, constantly work their way through the World Wide Web, finding, analysing and indexing web pages, it always helps to give them a little helping hand by submitting a Sitemap for them to crawl. Of course, there is no guarantee that this will increase the priority of your site, but it doesn’t help, and so it is advised.
One way to do this is via Google Webmaster Tools, where, once you validate your site, you can then point Google to your XML Sitemap. This suggests to Googlebot to have a look through the sitemap to make sure all of your pages are indexed.
A Sitemap is usually generated by your content management system, but there are other ways to generate a Sitemap if necessary. You could use a plugin such as Yoast, or an online Sitemap generator such as www.xml-sitemaps.com