Fear is a normal and healthy part of life. Fear plays an important role in keeping us from entering harmful situations and helping us decide when to get out of situations that are not necessarily the best. Under normal circumstances, fear can be managed through reason and logic. It does not take over our lives or cause us to become irrational.
Phobias, however, twists the normal fear response into something that is difficult or impossible to control. A type of anxiety disorder, usually defined as a persistent fear of an object or situation in which the sufferer commits to great lengths in avoiding despite the fear, typically disproportional to the actual danger posed, often being recognized as irrational.
The most common phobias are Spider, snakes and heights. Although there are many more suffered by many people of all ages.