What is the psychological explanation for the need to communicate?

I am researching (for personal enjoyment and knowledge) the five human needs: social, intellectual, emotional, spiritual, physical.

I believe all five are tightly connected. One thought I have is this: I do not understand why I feel the need to communicate. Something will stay in my mind UNTIL I talk about it, then I feel okay about it. I understand white personalities are more social, and being a white, I do not see how others can remain quiet in an otherwise social setting.

How do people keep to themselves? Why is their social needs different than mine? If you really ponder about it for a few minutes, it is fascinating to think about why you talk. Think about what you are saying, why you are saying it, and what you expect the other person to feel and reply.

After giving it a little thought, why do you communicate?
What does the world of psychology have to say about these questions?