Agoraphobia isn't the contrast of claustrophobia – but a lot of people think it is. In fact, I used to think precisely that. I used to think exactly that even when I was suffering from agoraphobia. I was even offered the opportunity to join an agoraphobics group, but I said no because I wasn't afraid of open spaces.
I quite liked open spaces as long as no one else was anywhere near me. In fact, if there was no other human being in sight, then that was OK as far as I was concerned. But that was all a very long time ago.
The translation of agoraphobia is 'fear of the marketplace', not, as many people think, fear of open spaces. The essence of the marketplace is people and human interaction. This is what is fearful.You can also navigate to http://myclaustrophobia.com/ to get more information about claustrophobia.
The fear is usually of showing oneself up in some way in the eyes of others. Typically agoraphobias worry about things like vomiting (usually as a result of severe anxiety); fainting; having a panic attack, or suffering from a genuine health emergency like a heart attack.
The concern is usually one of embarrassment – perhaps fainting and finding oneself on a supermarket floor gazing up into a circle of concerned faces who will insist on making a fuss and calling an ambulance.