XML Sitemap: an XML sitemap is an XML file that lists all of the URLs for a single website, as well as additional information, including when the page was last updated and how often it changes. This sitemap is used to help search engines identify searchable pages of a website and crawl these webpages more effectively. These files are now used as an alternative to an older method of collecting this information, in which a website would have to fill out a form and submit it via a search engine's submission page. Today, web developers either directly submit an XML sitemap or wait for a search engine to find it.
In order to submit the URLs in the sitemap, the syntax must be exact. For this reason, XML is typically the markup language used in these files because it is more precise than HTML coding. To further ensure that no errors are included, many people will use an XML syntax validator. Meanwhile, some people prefer to generate their URLs automatically by using either software or web applications created for that purpose. XML sitemaps can also be used to help navigate a website by providing a complete overview of the content available.