XML sitemap
An XML sitemap is a machine-readable file listing a website's important URLs to help search engines discover them.
In full
An XML sitemap is a structured file, conventionally at /sitemap.xml, listing the URLs a site owner considers worth crawling, optionally with the date each was last modified and a relative priority. Search engines use it to discover pages that internal linking might not surface, which makes it most valuable for large sites, new sites with few inbound links, and pages that are deep in the structure. It supplements crawling rather than replacing it. A sitemap should list only canonical, indexable URLs; including redirects, error pages, or noindexed pages reduces the trust an engine places in the file.
Why it matters
For a new domain with almost no inbound links, a sitemap submitted to Google Search Console and Bing Webmaster Tools is the fastest route to discovery.
A common misconception
That stamping every URL with today's date makes a site look fresh. Search engines discount last-modified dates on sitemaps where everything is always current.