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HTML Guide

Free site validation

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

The document is not mappable to XML 1.0 due to two consecutive hyphens in a comment.

Malformed comment syntax has been found, check out the affected comment.

HTML comments are helpful to leave notes about the code right next to it. To create a comment, it must start with <!-- and end with -->, as in this example:

<!-- Good comment -->

Comments can
be multi-line

A common cause for a malformed comment is using too many hyphens (-) as in this example:

<!-- Wrong comment -->

Related W3C validator issues