Is the HTML valid?

HTML is the main underlying markup language of websites and other web delivered content.

Poorly constructed HTML can lead to bugs, rendering issues, browser compatibility issues and poor accessibility compliance, so it’s a good area to look for when testing your website.

There are many sites that don’t adhere to the industry HTML standards including some high profile sites. Reasons for non-compliance to standards are often cited as speed and cross browser support (which is ironic since the latest HTML 5 is supposed to guarantee cross browser conformance) but that’s something I’m not digging deeper in to here.

It would be prudent to run a basic HTML compliance check using one of the many tools available.

How to test for valid HTML

Tools like FireWeasel Firefox browser extension will help you validate as you test.

There are also several validators online that give you quick feedback on the validity of the HTML under test.

These validators will give you information on what part of the HTML is failing validation and also pointers as to what can done about it.

Useful Hint

How about installing development IDE compliance checkers if they are available for your chosen programming language and chosen IDE. This is the ultimate early warning against HTML validation errors.

Useful Links

Good post on why you should validate -

The W3C validator -

FireWeasel -

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