What’s the difference between categories and tags? What’s the optimal number of WordPress categories? How many is too many? Is it okay to assign one post in multiple categories? Is there a limit of tags we can assign to each post? Do tags work like meta keywords? Are there any SEO advantage of using categories over tags or vice versa? We’ve seen quite a few commentaries on this subject through out the web, but we found that they were inconsistent and incomplete. If you ever had these questions, then hopefully they will be answered once you are done reading this post, so you can make adjustments to your blog if necessary.