Phobias are persistent and extreme fears that are out proportion with the actual threat posed. A phobia may be of an object or situation, with a strong desire to avoid the fear and, in some cases, an inability to function at normal tasks (such as a job or a social situation).

Phobias are among several anxiety disorders, which also include panic disorder, post-traumatic stress disorder, obsessive-compulsive disorder and generalised anxiety disorder. Unlike general anxiety disorders, a phobia is usually connected with something specific. Common specific phobias include those related to animals (e.g. snakes and spiders) and situational phobias, like fear of enclosed spaces (claustrophobia) or travelling in aeroplanes.