In Django models, there are three types of relationships that can be defined between models: OneToOneField, ForeignKey, and ManyToManyField.

OneToOneField creates a one-to-one relationship between two models, where each instance of one model is related to at most one instance of the other model. Example: marriage. Each person can only be married to one other person at a time.

ForeignKey creates a many-to-one relationship between two models, where each instance of one model can be related to many instances of the other model, but each instance of the other model can only be related to one instance of the first model. Example: boss and employees: A boss can have many employees, but each employee only has one boss.

ManyToManyField creates a many-to-many relationship between two models, where each instance of one model can be related to many instances of the other model, and vice versa. Example: party. Many people can attend the same party, and each person can attend many parties.