XML Sitemap
Definition
An XML sitemap is a file, usually at /sitemap.xml, listing the URLs you want search engines to crawl. Each entry carries the URL and optionally a lastmod date; Google ignores the changefreq and priority elements entirely, so they are not worth maintaining. A sitemap is a discovery aid, not a ranking factor — its value is highest on large sites, new sites with few inbound links, and sites where navigation buries content. Best practices: list only canonical, indexable URLs; exclude noindex pages, redirects, and duplicates; cap each file at 50,000 URLs or 50MB uncompressed and use a sitemap index beyond that; and generate it automatically so it never drifts from the site.
What are the size limits for an XML sitemap?
50,000 URLs or 50MB uncompressed per file, whichever comes first. Larger sites split across multiple sitemaps referenced by a sitemap index, which is itself capped at 50,000 sitemaps. Files may be gzipped, and the 50MB limit applies to the uncompressed size. Splitting by content type rather than arbitrarily is more useful, because Search Console reports coverage per sitemap.
Does submitting a sitemap get pages indexed?
No. A sitemap helps Google discover URLs; it does not oblige Google to index them. Pages routinely sit in 'Discovered — currently not indexed' despite being listed, which is a judgement about the page's value, not a crawling failure. Internal links are the stronger signal — a page reachable from your navigation and linked in context is treated as more important than one that only appears in a sitemap.
Should lastmod dates be accurate?
Yes, and Google now says it uses lastmod when the values are consistently truthful. The failure mode is a CMS that stamps every URL with today's date on each rebuild: once the dates are obviously unreliable, Google discounts them entirely and you lose a real recrawl signal. Update lastmod only when the page content actually changed.
What should never go in a sitemap?
Anything you are not asking Google to index: noindex pages, URLs that redirect, non-canonical duplicates, 404s, and pages blocked by robots.txt. Each one is a contradictory instruction, and Search Console flags them as sitemap errors or warnings. A sitemap listing URLs that 404 is a common and avoidable audit finding, usually caused by a generator reading from a stale source.
How do you tell Google where the sitemap is?
Two ways, and both are worth doing. Add a Sitemap: line to robots.txt, which any crawler reads without you registering anywhere. Then submit it in Search Console, which additionally gives you per-sitemap indexing reports. Note that the 'indexed' count shown per sitemap in the API is no longer populated and reads zero regardless of reality — use the Page Indexing report instead.
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