Of the three main tags, only the DESCRIPTION metatag needs to be used. The Keywords and Robot tags are less used and often ignored, but given the ever changing crawler ranking algorithms it doesn’t hurt to include Keywords and there are times when Robots will help in preventing negative effects of broken links on no content, link only pages. Some say it these last two are a waste of time, other say they still may help now or in the future. We here at UCANSEO are of the opinion that for the little time it takes to add them, just do it. The “KEYWORD” METATAG is considered rendered useless by old Black Hat SEO techniques. The crawlers apparently either ignore them or keep a low value assignment to them. For us they act as a reminder of the key words and phrases the page has been optimized for. This will become a set of crib notes to use if the page changes. If the Body Text changes, this can be a reference to make sure all the critical words and phrases are represented.