Phobias occur in several forms. 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.
 

Many people experience specific phobias, intense, irrational fears of certain things or situations- dogs, closed-in places, heights, escalators, tunnels, highway driving, water, flying, and injuries involving blood are a few of the more common ones. Phobias aren't just extreme fear; they are irrational fear. You may be able to ski the world's tallest mountains with ease but panic going above the 10th floor of an office building. Adults with phobias realize their fears are irrational, but often facing, or even thinking about facing, the feared object or situation brings on a panic attack or severe anxiety.

Specific phobias strike more than 1 in 10 people. No one knows just what causes them, though they seem to run in families and are a little more prevalent in women. Phobias usually first appear in adolescence or adulthood. They start suddenly and tend to be more persistent than childhood phobias; only about 20 percent of adult phobias vanish on their own. When children have specific phobias--for example, a fear of animals--those fears usually disappear over time, though they may continue into adulthood. No one knows why they hang on in some people and disappear in others.