What is Real Time Operating System?

From: Allen (sfbong_at_tm.net.my)
Date: 03/27/04 

Date: 26 Mar 2004 22:35:19 -0800

Hi,

I saw the word "RTOS" appeared many times in this group but have no
idea what it is. So could the experts here give me a brief idea what
is it in non-technical terms?

Which OSes in the market are qualified as RTOS?

Allen