Site maps can improve search engine optimization of a site by making sure that all the pages can be found. Most search engines will only follow a limited number of links from a page, so if a site is very large, the site map may be required so that search engines and visitors can access all content on the site. XML sitemaps have recently gained popularity since introduced by Google. MSN, Yahoo, Ask, and Google use the same protocol, having a sitemap lets the four biggest search engines have the updated page information. Sitemaps do not guarantee all links will be visited by the bot, and being visited by the bot does not guarantee that they will be indexed (which leads to high rankings). However, a sitemap is still the best insurance for getting a search engine to learn about your entire site.