XML Sitemap
A structured XML file listing all important URLs on a website to help search engines discover and prioritise them for crawling.
Definition
An XML sitemap is a file that lists the URLs on your website in a structured format, following the Sitemap Protocol (sitemaps.org). It helps search engines like Googlebot discover pages they might not find through normal link-following, particularly new content, pages with few internal links (orphan pages), and large sites with deep hierarchies.
Each URL entry in a sitemap can include optional metadata: <lastmod> (date of last modification, which helps prioritize re-crawls), <changefreq> (how often the page changes — a hint, not a directive), and <priority> (relative importance within the site, from 0.0 to 1.0). Google has stated that changefreq and priority are largely ignored in practice, but lastmod is a useful crawl prioritization signal if kept accurate.
XML sitemaps can be split into index sitemaps (a sitemap of sitemaps) for large sites, with each individual sitemap file limited to 50,000 URLs and 50MB uncompressed. Submit your sitemap URL via Google Search Console (and Bing Webmaster Tools) and reference it in your robots.txt file with a Sitemap: directive. Keep the sitemap up to date — including only canonical, indexable URLs — to avoid confusing crawlers with URLs that redirect or return noindex.