In one sentence
sitemap.xml is a file that lists all URLs in your site in XML format, telling search engines and AI crawlers "these are the pages on our site."
What does this look like in practice?
You create /sitemap.xml and write something like:
<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
<url>
<loc>https://example.com/</loc>
<lastmod>2026-05-24</lastmod>
<changefreq>weekly</changefreq>
</url>
<url>
<loc>https://example.com/pricing</loc>
<lastmod>2026-05-20</lastmod>
</url>
...
</urlset>