X-robots-tag
This is the meta-tag located in the header section of a web page that tells the search engine bots how to crawl and index your website.
XML
XML stands for Extensible Markup Language which is a language used by search engines to categorize and understand website data.
XML Sitemap
An XML Sitemap is a list of web pages on your website that is created and submitted to resources like Google Search Console to help search engines crawl and index your website better.