What is sitemap.xml
A sitemap.XML file is machine readable and lists the pages and posts on your website. Search Engines such as Google and Bing read this file to understand what content exists on your website.
For SEO reasons it’s recommended to have an up to date sitemap.XML file available for Search Engines. WordPress doesn’t generate this file however there are various plugins available that will automatically regenerate the file whenever relevant content is added or deleted such as WordPress SEO and Google XML Sitemaps.