Real Time is often mistaken for the meaning that something will happen immediately(Or extremely fast). But real time usually means the time that something takes to happen while being uninterrupted. So if I send a radio signal to mars and it takes lets say 5 days(exaggeration).. then whoever received the message at mars received it in Real-Time. Or lets say a computer game... you press the button on your mouse and then the time it takes the computer to do its calculations and to act upon that button press is done in Real-Time.
One definition is:
Code:
RealTime: Used to describe a system that must guarantee a response to an
external event within a given time. --Dictionary.com