It is one of the pathological forms of anxiety.

A phobia is an abnormal fear of an object or situation. Agoraphobia, for example, it is the fear of being in public places, surrounded by the crowd, and not being able to escape easily if he panicked. There are so many phobias: phobias of animals (mice, dogs, snakes, spiders…), phobias of situations (fear of enclosed spaces such as the elevator, tunnels, fear of heights, water, plane…), phobias social (fear of public speaking, agoraphobia, fear of blushing …), etc. Phobias are not just fears of objects or situations.
They are mostly irrational fears, unjustified or exaggerated compared to the cause that originates. The sufferer is aware that it is an irrational fear, but it cannot control that ultimate feeling of anxiety that, even, sometimes flows into panic. Many phobics do not suffer so much of their problem because what triggers the fear is easily avoidable (instead of taking the elevator, you opt for the stairs). But for other phobias severely affect work and social relationships. Sometimes phobias lead to depression or pathological behaviours (alcoholism …). The social phobic tends to under value and overestimate others. A mistake, a blunder, embarrass them well over the odds. Blush easily, they have the impression that all eyes are focused on them. The main fear is focused on this or that situation: public speaking, speaking to superiors, courting someone … In many cases, this handicap leads them to restrict drastically relationships and social life, except for some very close friend or relative.
The phobia can be treated with medication (anxiolytics, beta blockers, antidepressants) when you cannot avoid the situation that creates it. The most difficult cases require a recourse to psychotherapy.
Behavioural therapies are often effective, and can be associated with or without drugs. They work by comparing the subject to the cause of the phobia, in no dangerous situations, sometimes virtual, and are often associated with relaxation techniques.