In the Using abstract models for reusable model features recipe in Chapter 5, Application Models, the models.TransientModel base class was introduced. This class shares a lot with normal Models, except that the records of transient models are periodically cleaned up in the database; hence, the name transient. These are used to create wizards, or dialog boxes, which are filled in the user interface by the users and are generally used to perform actions on the persistent records of the database.