Denial of Service
Denial of service when talking about computer security is a type of attack where the intent is to deny service to the users of the service. The attack is normally directed against a computer system or a service running on that computer system. Several common denial of service attacks attempt to cause a computer to crash by sending them malformed network packets. Other attacks may use a ping attack or a request for service from many attacker controlled computers to overload a computer and prevent it from being able to respond.