extroverts and introverts.(Sometimes it's spelled extrAversion, sometimes extrOversion.) In my own words, extroverts draw energy from being with other people; being alone tends to drain them and leave them feeling a little limp and empty. Introverts, however, charge up their inner batteries during alone-time; interacting with the group is what tends to wear them out.
Being mainly an extrovert myself, for a long time I was confused and believed that "introverted" meant "shy;" I know now that introverts can be confident and outgoing, but that doing so is hard work and requires recharge time. I've also learned that if I don't get sufficient time alone to recharge, it's hard for me. The children in our classrooms also have these characteristics. I hope I respect them.
Alone in the Crowd
I have a seat
I have a spot
I have a place in line between my buddies.
But what I wish
that I could do
when it gets wild is hide inside my cubby.