Categories and tags are both WordPress taxonomies. They are used to group your posts together in different ways.
Categories are meant to broadly group your posts. Think of these as general topics or the table of contents for your WordPress site. Categories are hierarchical, which means you can create subcategories.
On the other hand, tags are meant to describe specific details of your posts. Think of these as your site’s index words. They let you micro-categorize your content. Tags are not hierarchical.
For example, this blog post on WPBeginner is in our category’ Beginners Guide’. You can see all the posts in this category by going to Blog » Beginners Guide in our navigation menu.
This post also has the following tags: categories, categories vs tags, custom taxonomy, SEO, SEO best practices, sorting your content, and tags.
You won’t see these tags displayed anywhere in the article. However, they do help users find this article in relevant searches on our blog.
One of the biggest differences between tags and categories is that all WordPress posts must be filed under a category, but they don’t need to have tags.
If you don’t give your post a category, then WordPress will automatically assign it to the default category. This is called ‘Uncategorized’, but it’s often helpful to rename the Uncategorized category to something like ‘Other’ or ‘Miscellaneous’.
Note: By default, only blog posts have categories and tags in WordPress. However, you can add categories and tags to your WordPress pages using a plugin.