Meta Keywords
Meta Keywords provide information (keywords) about a given Web page, often to help search engines categorize them correctly. They are inserted in the <head> section of the HTML and are not directly visible to a user visiting the site.
Due to abuse by website owners, Google and other major search engines tend to ignore the Meta Keywords tag nowadays.
Google does not use the keywords meta tag in web ranking
More then a decade ago, search engines judged pages only on the content of web pages, not any so-called "off-page" factors such as the links pointing to a web page. In those days, keyword meta tags quickly became an area where someone could stuff often-irrelevant keywords without typical visitors ever seeing those keywords. Because the keywords meta tag was so often abused, many years ago Google began disregarding the keywords meta tag.
Source: http://googlewebmastercentral.blogspot.com/2009/09/google-does-not-use-keywords-meta-tag.html