Value:
Indicates whether or not "all" of your
meta keywords are contained within
the page body. If any keywords are missing, this value will return false.
Background:
It was common years ago for web developers to spam meta keyword tags with unrelated
terms to bring more traffic to their site. While this practice has ceased due to
less importance being placed on the meta keyword tag, search engines still consider
this tag for search engine placement. Any kewords listed in the meta keywords tag
that cannot be found in the page body are now considered spam by most search engines..
Recommendation:
Having meta keywords that are not present in your page content may cause your page
to penalized. Therefore it is always recommended to ensure all meta keywords are
contained somewhere in your page content.