The terms introvert, social phobia and social anxiety all give rise to similar types of conditions. There is however a difference. Phobia, of course means fear of and so social phobia denotes fear of social situations. Simple shyness is generally social phobia light or social phobia in its early stages.
However, with one who is an introvert, fear is not an issue. An introvert simply works better, functions better and is genuinely happier when alone. Company tends to sap his/her energy and at certain times will make him/her miserable. For this reason an intorverted person will avoid social situations by choice but not out of fear. Introverts are often described as loners.
Of course, feeling uncomfortable with, or having ones creativity stifled by others is a neurosis, but it is not a phobia. Still, there are introverts in all walks of life. Many of them are very happy and certainly, well adjusted in many ways.
Many introverts will attend parties or family gatherings, but while they are engaged in such activities, their tendency is not to be seen as the bright people they are. In other words, they may act like or seem to be dullards when at social gatherings and few if any of the others attending these gatherings will ever realize they are, in fact quite the opposite of a dullard.
Because public schools involve a myriad of social activities and do in fact, place students into groups, some very intelligent introverts are very poor students. Sometimes, they even are mistakenly put into special classes.
These types of people will never hit their stride until they are out of school and out on their own. Because the benefits they derive from school are limited, they tend to be avid readers and are always pursuing knowledge.
In the long run, not being distracted by the need to look good to others actually give introverts an advantage over others when it comes to making discoveries or being successful in certain fields, such as writing.