XML Sitemaps
Google Sitemaps was introduced in June 2005 so web developers could publish lists of links from across their sites. The sitemap is used to make the search engine aware of the site and the pages on the site.
In 2007, XML sitemaps were supported by Google, Yahoo, Ask.com, MSN. The location of the Sitemap can be specified using a robots.txt file to help search engines find the Sitemaps.
As of 2013 XML sitemaps are supported by Bing and Yahoo, Google, Russian market leader Yandex, and the Chinese market leader Baidu.
Read more about this topic: Search Engine Submission