How Google takes into account meta tag Keywords?
In the official Google blog for webmasters on this occasion there is a message from Matt Cutts (works in group, which is engaged in the development of Google's search quality):
Google doesn't use the "keywords" meta tag in our web search ranking.
Does Google ever use the "keywords" meta tag in its web search ranking?
In a word, no. Our web search disregards keyword metatags completely.
Does this mean that Google will always ignore the keywords meta tag?
Google has ignored the keywords meta tag for years and currently we see no need to change that policy.
That is, Google ignores the meta tag "keywords" and will no longer take into account the most likely.
How Yandex takes into account meta tag Keywords?
It is written in the Yandex.Help that <meta name="Keywords" content="..."/> may be taken into account when determining whether the page searches.
That is, Keywords could be not taken into account by Yandex, and if they are, it is only under certain conditions.
How Rambler takes into account meta tag Keywords?
What is written in Rambler documentation on this occasion:
Robots of Rambler ignor when scanning the field <meta name="keywords"...> and all other fields <meta...>, except <meta name="robots"...>.
So that, Rambler ignores the "keywords" meta tag.
How Mail.ru takes into account meta tag Keywords?
In the information for webmasters the following is written: <meta name="Keywords" content="..."/> — may be taken into account while comparing conformity of the page with search queries.
That is, like in the case with Yandex Mail.ru Keywords could be not taken into account and they could be counted only under certain conditions.
To use or not to use... meta tag Keywords?
To use the Meta Keywords tag websites that are fully focused on the English-speaking audience, which Google uses, is not necessary.
If the site is focused on the Russian-speaking audience, which uses Yandex, Mail.ru - whether to use Keywords or not — you can make a decision by looking at competitors who are in the top of the search engines.