Contrary to some rumors, the validity of web pages according to the W3C a criterion that is used in the ranking of Google. 's Matt Cutts confirmed this in an appropriate screencast.

A majority of sites on the net does not contain a valid source , be it to support old browsers or because the validity in everyday life no importance is attached to. In general it can, however, of the validity of the source code is not close to the quality of the content and most current browsers provide even non-valid code correctly represents the consideration would lead to content that is potentially worse results because invalid websites would be disadvantaged.