Many of us may know what it feels like to be nervous before a party, or when meeting new people or making an important phone call. Those with social anxiety disorder have very intense versions of those fears — intense fears of being judged by others that cause them to avoid those kinds of situations. For most people, fears of social situations usually subside once the intimidating event has been faced. But in social anxiety disorder, these feelings are persistent and usually last for at least six months.
Social Anxiety Disorder;Fear of social situations in which the person is exposed to unfamiliar people or to possible scrutiny by others. The individual fears that he or she will act in a way (or show anxiety symptoms) that will be embarrassing and humiliating, often times leading to avoidance of social situations and severe distress when participation in social situations can't be avoided. 
Occasional anxiety is an expected part of life. You might feel anxious when faced with a problem at work, before taking a test, or before making an important decision. But anxiety disorders involve more than temporary worry or fear. For a person with an anxiety disorder, the anxiety does not go away and can get worse over time. The symptoms can interfere with daily activities such as job performance, school work, and relationships.