Sitemap
Short definition
A sitemap is a file, usually in XML, that lists every page on a site for a search engine to discover.
A search engine normally finds a site by following links, but a brand new page with no links pointing to it yet can go unnoticed for a while. A sitemap tells the search engine each page's address, when it last changed, and its rough priority.
On large, frequently updated sites, an online shop with thousands of products for instance, pages can go unnoticed for months without one. A sitemap is usually referenced inside robots.txt and also submitted directly to tools such as Search Console.
A sitemap is often confused with an HTML page built for visitors that lists a site's sections; the XML sitemap, by contrast, exists purely for search engines and never appears anywhere in the visible site. A common mistake is including pages that are blocked by robots.txt or marked noindex inside that sitemap; the contradiction sends a mixed signal to the search engine and weakens how much it trusts the file.
Why it matters
Without a sitemap, indexing new pages is left to chance. A correct sitemap makes sure a search engine sees every important page on time, rather than stumbling onto it eventually.
Illustrative example
A marketplace seller forgot to add three hundred new products to the sitemap, and most of them stayed invisible in search for a whole month.
