Google analysiert HTML Codes von 1 Mrd Webseiten und legt umfangreichste, ausführlich kommentierte (!!!!) Statistiken vor:
Various people have, over the last few years, done studies into the popularity of authoring techniques. For example, looking at what HTML ids and classes are most common, and at how many sites validate (and yes, we know that we’re not leading the way in terms of validation)…. We can now add to this data. In December 2005 we did an analysis of a sample of slightly over a billion documents, extracting information about popular class names, elements, attributes, and related metadata. The results we found are available below. We hope this is of use!
Webmaster Blog unterstreicht zB besonders einen Google-Kommentar zu den META-Statistiken: keywords, which these days is mostly useless, ironically, and description, which is still somewhat useful.