Categories vs tags

Before you get too many entries created, you might want to start organizing your blog so that content can be easily found. You can create categories as well as tags for your posts, then provide links to these categories or tags that you have created in a sidebar widget. Categories tend to be larger subjects that your blog might focus on, such as history or English; tags tend to more specific terms that a post is about, such as The War of 1812, or Edgar Allen Poe. You can add multiple tags or categories to posts.

Changing the default WordPress post category

Read about changing the default WordPress post category on this page.