Social inhibition is when a person restrains or alters their behavior when around others in a social setting for fear of being judged, or facing the disapproval of others. In many cases social inhibition is a normal and proper social behavior. You certainly act differently at a friend's party than you would at a grandparent's party.
However, too much or too little social inhibition can be a detrimental characteristic and can be problematic. If a person has too much social inhibition they may be so afraid of other people that they are too quiet and seem aloof or rude. If a person has too little social inhibition they may seem obnoxious and over the top to others by acting inappropriately. Social inhibition issues can be associated with some mental health problems.