Panic disorder is a type of anxiety disorder and is characterized by recurrent panic attacks.
A panic attack is a sudden episode of fear and anxiety without that fear stemming from any real danger or obvious cause. In panic disorder there is a unique combination of physical and psychological symptoms for each person.
People who have panic attacks are concerned about the possible consequences of the next panic attack and are tormented by thoughts such as, "What if I have a panic attack while driving?" Contrary to what the person is experiencing, a panic attack itself is not life threatening.