Socket, whiteout, FIFO, what's the meaning?

From: Pierre Thibault (p.thibault_at_bigfoot.com)
Date: 07/27/03 

Date: Sun, 27 Jul 2003 14:57:33 -0400

Hello,

I am a new unix user I would like to know what these words mean:

Socket;
Whiteout;
FIFO?

These are things that we can find in some directories and would like to
know the meaning of these words in this context.

Regards.

-------------------
Pierre