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HTML Guide

Free site validation

Find out what web pages on your sites are affected by HTML issues.

Start tag seen without seeing a doctype first. Expected “<!DOCTYPE html>”.

HTML documents are expected to start with a first line containing the Document Type Declaration, that defines the HTML version used. Since HTML5, it’s just <!DOCTYPE html>, which must appear before the start <html> tag.

Here’s an example of a minimal HTML5 document:

<!DOCTYPE html>

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