A violent crime is one when someone physically hurts or threatens to hurt a victim, and also includes crimes where a weapon is used.
Assault, murder and manslaughter, gang violence and domestic violence are all regarded as violent crimes. Sexual violence (such as rape or sexual assault) is also considered a violent crime, and there is a separate section on this website about 'understanding sex crimes'. Violent crime can also happen at home, this is called domestic abuse.
You can read more about this in the 'talking about abusive relationships' section.