Verifies that the page has a modern HTML doctype declaration.
The Document Type Declaration (Doctype) is the very first line of an HTML document. It tells the browser which version of HTML the page is written in.
A proper doctype ensures the browser renders the page in 'standards mode,' following modern web specifications. Without it, browsers may enter 'quirks mode,' which can lead to inconsistent and unpredictable visual rendering.
A missing or incorrect doctype can cause significant CSS and layout issues across different browsers.
<!DOCTYPE html>
<html>
<head>
...
</head>
<body>
...
</body>
</html>Run a free audit to see how your site performs on Doctype Test and 159 other checks.
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