The only way meta tags can harm your site is if you stuff them. Writing accurate, brief lists of meta tags certainly can't hurt - although at this point I think we're all aware that the actual content of your site is more important than anything else.

On a related note, meta descriptions are HUGELY important. Meta tags are just a little something extra you can do to help your site's search ranking. Unless you're following black hat practices there really isn't much in the way of SEO that ISN'T worth doing right.

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