Sitemaps are an easy way for webmasters to inform search engines about pages on their sites that are available for crawling.
Web crawlers usually discover pages from links within the site and from other sites. Sitemaps supplement this data to allow
crawlers that support Sitemaps to pick up all URLs in the Sitemap and learn about those URLs using the associated metadata.
Using the Sitemap protocol provides hints for web crawlers to do a better job of crawling your site.
In addition, you can also use Sitemaps to provide metadata about specific types of content on your site, including
video, images, mobile, News, software source code, and geographical (KML).