A panic attack in itself is not actually an anxiety disorder, but it can be a feature of any of the anxiety disorders. Panic attacks also can occur in the context of other psychological problems. Moreover, many people without any particular psychological disorder experience panic attacks from time to time.
The word panic comes from the name of the ancient Greek god Pan, who had the head and torso of a human and the hinquaters, legs, and horns of a goat, and who understandably inspired sudden fear amongst those who encountered him! Essentially, a panic attack is an episode of intense fear or discomfort that comes on quickly and includes a number of physical sensations or other symptons.
To be considered a full panic attack, the episode must include at least four of the following symptoms.
Racing or pounding heart
Trembling or shaking
Shortness of breath or smothering sensations
Chest pain or discomfort
Nausea or abdominal discomfort