The short answer to this question is: “Not as important as they used to be.”
Google claims that its algorithm does not factor in meta keywords when determining listing position. Yahoo still considers meta keywords, but the search engine doesn't place a lot of weight on them.
Where do meta keywords go?
Meta strategies provide an additional opportunity to add keywords to your site – in a way that readers won't see. You can use meta strategies judiciously by taking the opportunity to add meta tags to:
In Web design and SEO, you can use more than 30 meta tags and keywords per page. But SEO best practices advise limiting meta keywords to only about five to eight per page. Select the keywords that best reflect your content.