A machine-readable XML file listing the URLs you want search engines to know about, typically at
/sitemap.xml. Each URL can include optional metadata: <lastmod>, <changefreq>, and <priority> — though Google has stated it ignores changefreq and priority entirely and uses lastmod only when accurate. Maximum 50,000 URLs or 50 MB uncompressed per file; larger sites use a sitemap index. Submit via Google Search Console and Bing Webmaster Tools, and reference from robots.txt with Sitemap: https://example.com/sitemap.xml.