Setting up the proper structure for your content not only makes it easier for your visitors to find what they're looking for, but it also helps the search engines find and index your content. Although both categories and tags can be used to organize your content, they are not the same thing. Categories break your website into sections that organize your site in a hierarchy, making it easier for users to locate information related to a certain topic through WordPress' built-in navigation. Tags, on the other hand, are free-form identifiers. The tags you use for a given post usually include the primary keyword, as well as any secondary or long tail keywords you hope to be able to rank for with that WordPress Post.