Meta Keywords are a list of terms that will appear in the meta keyword element of an HTML header. This header is stored on every webpage, which means that Meta Keywords can be placed on any or all of the pages of a website – with different keywords or similar keywords.
Unfortunately, Meta Keywords have proven an effective location for keyword stuffing, or the practice of adding many keywords to a section of a website in order to boost its page rank for certain keywords. As such, Meta Keywords no longer affect the page rank of any page, as of 2009.