Ontology with a set of individual instances of classes constitute a knowledge base. Classes describe concepts in the domain. A class can have subclasses that represent concepts that are more specific than the superclass. Slots describe properties of classes and instances.

A slot type defines how the bot will process the information available in the identified slot. Each slot must be mapped to a slot type. Slot type help the bot define the information that the bot should look for when trying to find a slot in the utterance.