What are Django signals and when to use them?

Signals allow decoupled applications to get notified when actions occur. Common signals: • pre_save, post_save • pre_delete, post_delete • m2m_changed Use cases: • Logging • Cache invalidation • Email notifications • Profile creation Example: @receiver(post_save, sender=User) def create_profile(sender, instance, created, **kwargs): # Profile creation logic Benefits: • Loose coupling • Event-driven architecture