A specific phobia is a fear of a particular object or situation.
Social phobia is a fear of being painfully embarrassed in a social setting.
And agoraphobia, which often accompanies panic disorder, is a fear of being in any situation that might provoke a panic attack, or from which escape might be difficult if one occurred. It's an awful feeling when that airplane door closes and I feel trapped. My heart pounds and I sweat bullets. If somebody starts talking to me, I get very stiff and preoccupied. When the airplane starts to ascend, it just reinforces that feeling that I can't get out.