Compliance to W3C recommendation means following guidelines set by the organization. One such guidelines is document text declaration or DTD in short. For optimum website design it is best to follow the recommendation made by the World wide web consortium.
The effort is create properly structured pages that speak to International audience uniformly and in cases to specific linguistic audience. The effort to standardize web site development technology is what W3C is aiming at.
When making DTD the < meta > tag should be placed just after the as this is to override default browser setting for character sets. Not many web designers know about this fact. Correctly placing the DTD helps the the latest version of browsers and earlier versions as well to properly render the page on the users web browser.
A website that does not contain the DTD tag does not conform to W3C recommendations. When you implement the tag correctly on the web pages it leads to compliance of W3C standards. Web designers should make a detailed study of W3C recommendation for declaring character sets on web pages as per the language used on the web page. Example for web page with mixed language structure should use UTF-8 as follows:
Thus character set enabled on webpage will render the text correctly on the users browsers.