About one-third to one-half of the world's population is introverted, but the world considers such people second-class citizens, according Susan Cain, author of the book Quiet: The Power Of Introverts In A World That Can't Stop Talking. But Cain makes the case that introverts contribute just as much if not more to society than do extroverts. Despite this, as a society we idealize the extrovert, the smooth-talking people-persons that capture the attention of whatever room they're in. We shouldn't.
Cain argues that this extrovert ideal is rather new, having gained strength only in recent generations in the West. Other cultures (e.g. Asian) don't have this same ideal, and it is to their advantage. In Western culture, however, introverted children are made to feel ashamed and forced to behave in ways that are unnatural to them.
But introversion has its advantages, which we shouldn't be trying to change, according to Cain. She discusses a number of inventions and businesses (including Warren Buffett's Berkshire Hathaway) that wouldn't exist without the introspection that was required of its leaders. This introspection is something that only introverts appear capable of. By continuously marching towards this extrovert ideal, we are harming our society.
The book's discussion is centered around a number of anecdotes (e.g. Cain's own experiences, and ones she sought out for the purpose of the book, including a Tony Robbins seminar and a trip to Harvard Business School) and studies Cain cites. Myself, I don't love it when authors generalize anecdotes (i.e. I'm a firm believer that "the plural of anecdote is not data"), nor do I like to put a lot of stock in a collection of secondary data. After all, the results of most published studies cannot be replicated, and one can't possibly know which ones when they are discussed only in passing in order to support a point. Since you can find a number of studies which contradict each other, an author looking to support a point of view can just hand-select the most favourable one!
That said, Cain offers some food for thought, and this book is definitely worth a read if the topic interests you.