Are you an introvert? Do you have a friend or loved one who is an introvert? The answer is most likely yes to one of those questions, and if you are an extrovert, your introverted companion may sometimes leave you puzzled and frustrated. You, in turn, may leave him or her equally puzzled and frustrated.
Though estimates vary quite a bit, roughly 3/4 of people are extroverts (also spelled extraverts) and 1/4 are introverts. While the high energy, high social needs, and talkativeness of extroversion is valued more highly in US society, there is nothing abnormal or wrong about the lower-key behavior of introverts.
I came across a great blog called The Introvert's Corner written by Sophia Dembling at the Psychology Today website. I highly recommend it for both introverts and extroverts.