Sitemap Index File
A sitemap index is a special XML file that references multiple individual sitemap files — required when a single sitemap exceeds 50,000 URLs or 50 MB and useful for organising sitemaps by content type.
In context
Sitemap index files let large sites split sitemaps logically (one per content cluster, content type, or region) while exposing a single submission URL to Search Console. The index file follows the sitemap.org schema with sitemap entries instead of url entries. Submit only the index URL to Search Console; the engines crawl the children. Sub-sitemaps can themselves be capped at 50,000 URLs or 50 MB.
Toronto SEO's sitemap.xml is an index referencing 37 sub-sitemaps (cities, industries, glossary, comparisons, etc.) totalling ~5,500 URLs — clean organisation that scales as content grows.
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