Meta keywords tag does not work
Long ago when the internet was just a baby and was growing up, the meta keywords tag was used to target keywords that were relevant to your page. Search engines used to scan this tag and give your page extra points in their algorithms for each word inside the tag that related to your page. Very quickly web developers pounced on this fact and abused it to the point of oblivion. But nowadays you should not use the meta keywords tag as it does not work anymore.
What happened was a couple of things. The first was keyword stuffing. Web developers would put as many keywords and related words into the meta keywords tag and ended up ranking better in the search engines. This was an unfair practice and forced the meta keywords tag to be eliminated from the algorithms that scanned websites.
The second problem with the meta keywords tag was that companies would put their competitors names and keywords within their own pages. This caused search engines to get confused and sometimes a competitor would rank better for company names than the actual company themselves!
After these two problems were found algorithms were changed very quickly and this was done many years ago. The funny thing is a lot of SEO companies are still advocating the use of meta keywords and some don't even know that they aren't scanned anymore. We've heard companies tell us that you should put misspellings in the tag and that helps. This is an incorrect statement and all other statements about the meta keywords tag are generally false as well.
You should not use the meta keywords tag and it is actually detrimental to your site if you do. What you are effectively doing is adding extra superfluous content to your site which increases download times, increases page size and increases the bandwidth that your website uses. This all results in decreased customer satisfaction and increased costs.
Do not use the meta keywords tag.