For example, using an HTML 4.01 DOCTYPE, bgcolor="fffff" is accepted as valid for the "body" element even though the value "fffff" is missing a preceding '#' character and contains only five (instead of six) hexadecimal digits.

Also, for the "img" element, width="really wide" is also accepted as valid.

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While many veterans have learned to create error-free code and make relatively few validation errors, most beginners make more errors.

Computer validation checks can help beginners learn from their mistakes.

“These technologies, which we call “web standards,” are carefully designed to deliver the greatest benefits to the greatest number of web users while ensuring the long-term viability of any document published on the web. Improved Website User Experience W3C validated websites will be easily accessed by people with modern browsers.

Validation improves usability and functionality because your users are less likely to run into errors when displayed on browsers compared to non-validated websites.

DTD-based validators are technically not able to test for these types of attribute value problems.

Pages may not display as intended in all browsers, even in the absence of validation errors and successful display in other browsers.

You can use code that places either buttons or text links onto your page.

Place this code within the The text links will look like this on your page: Valid HTML 5 Valid CSS Note that the W3C has not yet released official button images for HTMl 5 validation as it has for the other standards, as seen below.

The Markup Validation Service is a validator by the World Wide Web Consortium (W3C) that allows Internet users to check HTML and XHTML documents for well-formed markup.

Markup validation is an important step towards ensuring the technical quality of web pages.

Websites that are not validated may display correctly in one browser but not in other browsers. Websites that are not validated may display formatting problems when used in certain browsers.