What is the role and purpose of proxy objects in Hibernate?

In Hibernate, proxy objects are used to implement lazy loading. Instead of immediately loading related entities from the database, Hibernate creates a proxy — a special placeholder object that contains only the identifier. When data is first accessed, the proxy automatically loads the full entity from the database.

This allows optimizing performance by reducing the number of queries and the amount of data loaded.

Example:

@Entity
class User {
    @Id
    private Long id;

    @OneToOne(fetch = FetchType.LAZY)
    private Profile profile; // profile is loaded through a proxy
}

Here, the profile field will be a proxy object until it is accessed.