Barking on the leash, fighting, defending the sofa, and growling at the garden fence. Canine aggression has many faces, its causes are diverse, and it is one of the most commonly mentioned dog problems. However, it is part of the normal behavior of every dog and cannot be completely trained out. The authors explain the background: How does aggression develop, how can it be avoided, and how should dog owners properly handle it? A current topic that affects almost every dog owner.