What it is
Every web page, underneath whatever it visually looks like, is built out of HTML — a set of labeled sections called "tags" that tell a browser what each part of the page is. Three tags form the skeleton every single page is supposed to have: <html> (marks the whole document as a web page), <head> (holds behind-the-scenes information like the page title and description, none of which is shown directly on the page), and <body> (holds everything a visitor actually sees and can click on).
This basic HTML structure check simply confirms all three of those wrapper tags are present and used correctly, rather than the page's content being dumped in without any of this scaffolding around it.
Why it matters
Browsers are very forgiving and will usually still display a page even when this structure is missing or broken, which is exactly why the problem can go unnoticed for a long time. But search engines, screen readers, translation tools, and browser extensions all lean on this structure to figure out where the real content starts and where behind-the-scenes information lives — without it, they're left guessing, and guessing sometimes goes wrong.
A page missing this basic scaffolding is also a common sign of something upstream being broken — a build process that failed partway, a template that got corrupted, or content management software outputting a fragment instead of a full page.
How to fix it
- View your page's raw HTML (in most browsers: right-click the page and choose "View Page Source", or press
Ctrl+U/Cmd+Option+U). - Confirm the very first tag is
<html>, followed by a<head>section, followed by a<body>section that wraps all the visible content. - If you're using a website builder (Squarespace, Wix, Webflow, WordPress), this structure is generated for you automatically — a missing structure usually points to a custom code embed or template that's interfering, so check any custom HTML blocks you've added.
- If you manage your own template or static site generator, confirm the base template file wraps every page's content in these three tags and hasn't been accidentally edited.
- Re-run your Launch Readiness check afterward to confirm the structure is now detected correctly.