Categories are words or phrases through which users can add content to predefined groups. As an administrator, you define categories in a way that's specific to a particular place (a space or social group, for example). As you create categories, think about how the place's content should be grouped. You can optionally associate certain tags with the category. If you do, someone who uses those tags with content will see the category's name highlighted. This is a cue to consider assigning the content to the category.
By creating or editing categories, you can help ensure that content is organized in the best way for people using the space.