The direction of a relationship can be either bidirectional or unidirectional.
A bidirectional relationship has both an owning side and an inverse side or not-owning side.
A unidirectional relationship has only an owning side.
Unidirectional: one side does not know about the relation.
In a unidirectional relationship, only one entity has JPA @Annotations: @JoinColumn and @ManyToOne
Bidirectional relationship provides navigational access in both directions,
In a bidirectional relationship, each entity has a relationship field or property that refers to the other entity.