Generalized social anxiety or social phobia - usually manifest as being extremely shy, or fear being around nearly everyone and most situations and anxiety treatment is needed to function in day to day situations.
Specific social anxiety - which is only experienced in specific situations such as stage fright. When away from that situation, you feel little to no anxiety during other social functions.
Most common symptoms of social anxiety are fear of anxiety being noticed, shortness of breath, rapid heart beating, chest tightness, blushing, shaking, and problems talking. When symptoms appear people become more self conscious. These symptoms can become worse if untreated.