There are many different kinds of phobias and, according to the National Institute of Mental Health, 15 million Americans over the age of 18 suffer from a social anxiety. That number rises to 19.2 million for specific phobias, which is 8.7 percent of adults. Despite the prevalence of phobias most people don't even understand what a phobia is or what it means to have one. However phobias are not that difficult to understand once you begin to learn about them.
The term phobia is used commonly to refer to any fear that is extreme. Many people refer to themselves as an arachnophobe if they are afraid of spiders. However, a fear is only a phobia if it is so severe that it causes you to avoid the situations that you fear. For instance, you are only afraid of flying if it terrifies you to fly to visit a friend of relative, but you still go. You have a phobia of flying if you're willing to turn down a desired job promotion because you would have to fly somewhere to accept it.
Many people don't understand how someone could have such an intense and irrational fear, despite most of us having irrational fears of our own, even if they are not as severe. The avoidance which defines a phobia and makes it seem so unusual is usually caused by the relief felt when someone with a phobia leaves a phobic situation. The relief acts as a reward for avoiding it and reinforces the behavior, so that the next time the situation comes up, the person seeks to avoid it.
The most common form of phobia is the specific phobia. This refers to what most people think of when they think of phobias. A specific phobia is the fear of a particular thing. Some common ones are arachnophobia, fear of spiders; acrophobia, fear of heights; emetophobia, fear of vomiting or being around vomiting; mysophobia, fear of germs (commonly referred to as germaphobia); and claustrophobia, fear of confined spaces.
The next most common type of phobia is the social phobia. Social phobias can seem like extreme shyness. People with generalized social phobia are usually afraid of humiliation and embarrassment while in a social situation. This can lead to the avoidance of social situations. Mild versions of social phobias are very common and almost everyone has felt the fear of embarrassment that characterizes this phobia, usually before a big speech or meeting someone important.
The last common form of phobia is agoraphobia. Agoraphobia is usually defined as a fear of open spaces, but this is a misleading description. Agoraphobia is most commonly developed by those who already have Panic Disorder. People with Panic Disorder suffer from panic attacks, a wave of extreme fear lasting several minutes that can have the symptoms similar to a heart attack. Panic attacks can be triggered by something or occur somewhat randomly. Panic attacks can be debilitating and embarrassing, so suffering one at a location where it is difficult to manage or hide, such as a shopping mall or while driving, can cause added stress and fear. A person who has suffered one at a location like that may then begin to avoid those locations for fear of having a panic attack there again. In a way agoraphobia is a fear of panic attacks, but it associates the fear with the location, not the attack. In time, a person can learn to associate fear and dread with that location separate from the panic attacks, which means they can continue having agoraphobia even if they cease having panic attacks. Also, in rarer cases, agoraphobia can develop without the pre-existing Panic Disorder.
National Institute of Mental Health, The Numbers Count: Mental Disorders in America, http://www.nimh.nih.gov