XML sitemap acts as a route map for the search spiders to let them find what you want indexed on your website.
Every webpage that doesn’t have a link from your website (Isolated/Orphaned pages) can also be indexed by search spiders, if they are written down in the XML sitemaps.
An up-to-date sitemap.xml file will ensure every web page on your website is listed on search engines with the latest content.
There are a number of free online tools that can automatically generate a sitemap.xml file for you.
