HTML Structure
A well-formed HTML document requires specific structural elements in specific positions: a single <head>, a single <body>, content starting within the <html> element. Malformed document structure causes browsers and crawlers to apply error-correction logic, which may produce different parsing results than intended. These six checks identify fundamental HTML structure failures.
No <head> element — the browser creates an implicit head, often with incorrect boundaries.
More than one <head> element — only the first is processed; content in subsequent heads may be misinterpreted.
No <body> element — browsers create an implicit body but structured parsing may be affected.
More than one <body> element — the second body is treated as body content by parsers.
Visible content or markup appears before the <html> element — breaks document structure.
The HTML document size is very large — crawlers may only process part of the document.
Audit HTML structureacross your site
A full audit checks every page for fundamental HTML structure issues that affect browser and crawler parsing.