Tags or tags words are another pre-defined taxonomy that WordPress uses to organize posts. They are similar to Categories, but while a Category may represent a broad topic of information (like a chapter in a book), a tag will be smaller in scope. You can think of them like keywords that represent your posts. (Or hashtags in Twitter #thisisahashtag)
For an example, let's use a blog that review books. If you have a category about books, you may also have tags such as non-fiction, fiction, H.G. Wells, etc that can be assigned to different posts. It would get tedious to create separate categories for each author and genre, but some users may want to see all of your posts about nonfiction books or target a specific author. Tags give you that second layer of organization that you can use to set up your content.
To be honest, I don’t usually use very often on my blogs. I use them when I want to create a special menu that only includes items that have a specific tag. Other than that specific use case, I find that categories give me plenty of options for organizing my content. But, if you have a certain subject area or category on your site that would work well with tags you should definitely use them. They are a great way to give your visitors other blog posts to read if they enjoyed your content.
Each post will show the tags that are assigned to it at the top or bottom of the text.
WordPress also has built-in sidebar elements that will show what is called a Tag Cloud. It will show the frequently used tags so your visitors can jump to all the posts that contain a specific tag if they are interested. We'll walk through sidebar elements in a future lesson.
In the Edit Post view, there is a box on the right hand side where you can add and remove tags as well as see the most frequently used tags.