What is a sitemap-index?

A sitemap-index is an XML file that references multiple child sitemaps instead of listing URLs directly. It uses the <sitemapindex> root element and one <sitemap><loc> entry per child sitemap. Sites need one whenever their URL count exceeds the 50,000-per-file protocol limit, or whenever they want to split content for cleaner Search Console reporting (one child per pages, posts, products, etc.). When you convert a sitemap-index to CSV, the converter follows every child and merges all URLs into one flat file — xmlsitemapmaker.com adds a Source Sitemap column so you can trace each URL back to its child sitemap. Search Console only needs the index URL submitted, not each child individually.