Violence is aggression, usually physical aggression that causes harm. Beating someone up, kicking a puppy, or attacking a defenseless village are all forms of violence.
From wars and acts of terrorism to bar brawls, violence is unfortunately very common in the world — and when there's violence, people get hurt. But you'll see a lot of organized violence and acts of aggression in sports: boxing and football are extremely violent, which is why people who play those sports get so many injuries. We can also say that something powerful or wild happens with violence, like a destructive tornado.
