World Wide Web Consortium (W3C) allows internet users to check HTML and XHTML documents for well-formatted markup.
HTML Tidy is another option for validating pages, though it may not offer the exact same results as the W3C validator.
One advantage of HTML Tidy is using an extension you can check your pages directly in the browser without having to visit one of the validators sites.
If your page isn’t displaying as expected a validator might very well point you to the cause of the display problems.
Also invalid code that may display fine in one document may cause show stopping errors in another because of the encompassing code.
Errors in your code can affect your sites performance and also make a big impact on you sites SEO, search engines check the HTML or XHTML code of your website when searching.
If they find invalid HTML or XHTML code – meaning code that does not follow the official rules, you might be removed from their indexes.
HTML Validator: This validator checks the markup validity of web documents in HTML, XHTML, SMIL, Math ML, etc CSS Validator: This validator checks the CSS validity of web documents in HTML, XHTML etc.
There are plenty of browser extensions that will test the page you’re viewing against the W3C validators.
If there is an error on your web page code, robots will stop searching your whole websites content.2.
Validation helps teach best practices Having standards-compliant code is the best practice for web design.
The following topics tell you more about validation controls and how to use them.