Are you unsure of your status as an introvert or an extrovert? There are plenty of quizzes online to help.
http://www.psychologytoday.com/blog/quiet-the-power-introverts/201103/quiz-are-you-introvert-or-extrovert-and-why-it-matters
http://www.humanmetrics.com/cgi-win/jtypes2.asp