Social phobia or Social Anxiety Disorder is an anxiety disorder, in which the characteristic fear consists in believing that you are observed and negatively judged in social situations or while carrying out an activity in public. What is mainly feared is the negative judgment of others. Generally, people with this disorder fear, in social and otherwise unfamiliar situations, that they will be able to say or do embarrassing things and to be judged anxious, clumsy, stupid, incompetent, strange, clumsy, weak or “crazy”.
The person affected by the disorder generally
Has this fear when he talks to others, when he does or says something while others are watching him or even simply if there is the possibility of attracting the attention of others; for example he is afraid of being misjudged by others if they realize he is anxious (blushes, sweats, trembles).
Or he fears he might say or do something wrong or embarrassing, look awkward, or have a panic attack (eg he often has thoughts like “… Now I will look awkward, awkward … I will start shaking and sweating … others will notice and they will laugh at me! “). Still others may feel anxious that others may find themselves unpleasant and / or criticize their appearance.
Generally the most commonly feared situations are:
Speaking in public, going to a party, writing or signing in front of someone, queuing up, using the telephone in public, using public transport.
Some people fear, for example, of having embarrassing physiological reactions (e.g. losing bladder control, throwing up, burping, etc.) and again, some are more afraid of situations in which they are asked for a performance, others, instead, of occasions for social interaction: typical examples of this last case are expressed in situations in which the person affected by the disorder fears that he has nothing to say or say something wrong, that he will be boring or, in any case, inadequate.
These fears may be present only in some social situations (specific social phobia) or in the majority of them (generalized social phobia).
In any case, the person suffering from social phobia faces such situations with extreme discomfort and anxiety, so often, in order not to experience such unpleasant sensations, he will begin to avoid the feared social situations in every way, with the idea that he will be well avoiding exposure to them.
The reasons for avoidance may be different: you may experience such intense anxiety that it is unmanageable or you may be tired of dealing with situations in which you fight against your own feeling of inadequacy. In some cases, avoidances can lead to the person’s social isolation.
The so-called “anticipatory anxiety” is also typical:
Anxiety itself has an evolutionarily “anticipatory” function, in the sense that it is an emotional signal that warns us, in terms of forecasting hypotheses, that our purpose could be compromised; in fact, before facing a feared event (e.g. a student who has to take an exam) a person may feel anxious because in advance he repeatedly imagines the occurrence of that event, perhaps with images of himself in which he will make a bad impression, will be awkward, it will look stupid. 
Summary
The images of what is feared may appear for days before having to face the feared event, thus increasing the level of anxiety. On some occasions, anxiety can become so intense that it really hinders the subject in carrying out his tasks.
During a meeting, for example, he could be so anxious as to be really unclear in explaining concepts. Therefore, those suffering from social phobia, when they have a very high level of anxiety, can really have poor performance.
The realization of what is most feared usually causes further embarrassment, shame or a sense of humiliation. A vicious circle can thus be established that feeds the disorder over time, as it maintains the fear of negative judgment and anticipatory anxiety over time.