Agoraphobia is a fear of open spaces or busy public places (literally a 'fear of market places'). Some people are so badly affected they become housebound. Claustrophobia is a fear of enclosed spaces, like crowded trains or lifts. Social phobia is a fear of embarrassing yourself in front of other people - at parties, or when eating or speaking in public, for example. Agoraphobia affects twice as many women as men, whereas social phobia affects men and women almost equally.