However, they can contain headings, paragraphs, lists, etc.
The META tag for this page might look something like this: Note that the attribute NAME defines what kind of META tag is being used, and the CONTENT attribute gives a list of key words and phrases that describe your page. You should put some serious effort into deciding exactly what keywords your page will use.
Meta tags are added to the While technically not a meta tag, this tag is often used together with the "description".
The contents of this tag are generally shown as the title in search results (and of course in the user's browser).
The Common Crawl, which is an incredible resource that all SEOs should be at least mindful of, has developed a microsite called the Web Data Commons where they identify trends extracted from the Common Crawl corpus.
Schema.org, the new vocabulary that search engines have forced us to learn without providing too much immediate benefit, appeared in 43.05% of the 1,811,471,956 typed entities that appeared in the 3,005,629,093 URLs on the 40,600,000 domains that make up the August 2012 Common Crawl Corpus.