Should I spend time on meta keywords tags?

Matt's answer:

Ryan, in Dearborn, Michigan, asks: “Can you think of any reason, whatsoever, to validate spending more than five minutes creating meta keywords?” Well, we have done a post and a video to say that we don’t use the meta keywords tag– uh the keyword meta tag in our rankings. So I wouldn’t spend even zero minutes on it, personally. Uh, now that’s not to say that you shouldn’t spend any time on any meta tag. Specifically the description meta tag; we are often willing to use that as our snippet, if we think it’s useful to show in the search results. If we don’t, or we think you’ve repeated the same meta description all over your site, and so maybe there’s not as much good information there, then we are more likely to draw the snippet from parts of the page as we saw it whenever we crawled. But, if you can come up with a good meta description, that can often entice users to click on your page, because they think they are going to find good, useful information. Now, you don’t want to do that deceptively and say: I have information about, you know, cartoons and then you click and it’s a porn site. But in general, it is worth some time looking at your description meta tag. Keyword meta tags? I wouldn’t spend any time at all on that, personally.

by Matt Cutts - Google's Head of Search Quality Team

Original video: