lastmod is an element in the XML sitemap indicating when a URL's main content was last significantly changed. It is only useful when maintained reliably.Open glossary entry → is an optional element in the An XML sitemap is a machine-readable file listing a website's important URLs. It helps search engines discover content more efficiently but does not replace internal linking or guarantee indexing.Open glossary entry →. It indicates when a URL's main content last changed significantly and can serve crawlers as an update hint.
Examples:
<lastmod>2026-06-08</lastmod><lastmod>2026-06-08T13:45:00+02:00</lastmod>
The date should reflect only genuine content changes, such as new text, updated facts or changed prices. Minor adjustments like a changed footer year, a new tracking script or a pure deploy are not sufficient reasons.
A common mistake is the "always today" pattern: the A content management system (CMS) is software for creating, managing and publishing web content, usually without programming knowledge. Well-known examples are WordPress or Shopify.Open glossary entry → sets every URL to the current date on each deploy. Then all pages look equally fresh and the signal loses value. A missing lastmod is less problematic than an incorrect one.