introverts, extroverts, and the observer types

In this world populated by over 4 billion people, it is hard for one to believe that
everyone may have something in common. It is true that each human has a unique
personality which defines them as an individual, but even the personalities are alike in one
way or another. Personalities can fall into three different categories: shy, outgoing, or the
undecided, obeservant personality.
The shy personality type can also be classified as the introverted personality.
Introverted is defined by a person who tends to shrink from social contacts; to concentrates
(one’s interests) upon ones self. This means that this modest type of people will become
one with the background, when in a social situation. For instance, a close friend, Jill, is a
very introverted person. She will open up at times, but normallly she does not speak up in
large groups of people. In situations where she is one on one with another friend, she can
be a rambunxious person, who is a complete joker...