Category is an outcome type that will tell a user what category they fall into based on what answers they pick.
For example, for a quiz titled "What kind of animal are you?" the categories may be "You are a dog" or "You are a cat".
Quizpipe will add all of the user's answers together, and assign them the category that they matched with the most. For instance, if they picked four answers that were mapped to "You are a dog" and three answers mapped to "You are a cat", the dog outcome will display at the end of the quiz.
If you are unclear on how to map your answers to particular outcomes, please read How does mapping work?