What are Sitemaps?
Sitemaps are a web way for webmasters to tell search engines about pages on websites that are available for crawling.
it is the simplest way, a Sitemap is an XML/HTML file that lists URLs for a website along with metadata about each website URL so that search engines can more easily crawl the site.
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 does not guarantee that web pages are included in search engines, but provides hints for web crawlers to do a better job of crawling your site.