A phobia is a specific fear, for instance a fear of water, snakes, or heights. Phobias are intense fears that are unrealistic or overblown. Often, people avoid the thing they are afraid of. This can lead to a loss of activities in life (i.e. avoiding a party if you know the hostess has a dog or not going to the Caribbean because you are afraid to fly), as well as a reinforcement of the fear itself.