Categories and tags are used as a way to organise your blog posts in WordPress, but there is often confusion about the difference between them and the purpose they serve. Categories and tags also have implications for SEO. I won’t go into that here, but generally if you aim to give visitors the best user experience possible, you will receive the SEO benefits.
When a user arrives at your blog, categories and tags allow them to view your blog posts by topic rather than the order they were written in (which is usually how blog posts are presented). Imagine a site where there are hundreds of blog posts how would anyone find something they were interested in reading without looking through all the posts? That’s right – by looking at the categories and tags.
Categories are meant to broadly group your posts. If you think of your blog as a book, categories would be equivalent to chapter titles. Typically a post would be assigned to just one category (using the book analogy – a section of a book would only appear in one chapter). I would put this post in my “Blogging” category.
Tags are meant to indicate the details of what the post is about. To use the book analogy again, tags are like the index of a book. I would use the tags “categories, tags, WordPress” for this post.
It’s worthwhile thinking about the categories you might use when you start your blog as it may have implications for the URLs of your posts. If your URL structure includes “/category/postname” then changing your categories will create new URLs and the old addresses will no longer work. In this case it is possible to set up redirections but of course it is extra work.
In summary, categories and tags are both important tools for organising your blog posts, but you need to use them wisely for them to be effective. I would review your use of them occasionally to make sure things are as they should be, because as your blog develops you may find it takes a direction you would never have imagined when you started.