Search engines read this file to crawl your website more efficiently. A sitemap tells the search engine, e.g. Google, which pages and files are important on your website. In addition, the sitemap provides valuable information about these pages and files. If it is a website, this information could include, for example, when the page was last updated, how often the page changes, and any alternative language versions of the page.
A sitemap can be created in several ways. You can make a manual sitemap, where you list all of them with links to the pages. You can program your way out of making a sitemap, so that every time you create a new page, a link is added to the sitemap.
An XML sitemap is not a guarantee that all your pages and subpages will be indexed, and it doesn't always make your placements in the search engine results much better. There are, however, certain advantages. The search engines are notified directly when you publish something on your website, and the same applies when you update pages.
It all depends on which platform you use. Typically, most modern CMS systems have plugins available that can generate XML files for you and publish them as a subpage. Examples include Yoast SEO, XML-Sitemap and WordPress, etc. If you have already created a sitemap, you need to give the search engines access to it. Google Search Console and Bing Webmaster Tools are effective guides that can help you on your way.
