stability of control system

Hi everyone,
I am studying control theory and I read the topic of position of closed loop poles.It is written that for the system to be stable,the closed loop poles must lie on the left half s-plane.I dont understand why?
Is it that if the poles lie on the right half s-plane,the output of system will grow without bound.
I hope to get some help
Thanks

The position of the poles determines the gain and phase of the feedback. The open-loop phase must be less than 180 degrees when the feedback gain is >1 for the loop to be stable. Otherwise the loop may oscillate (grow without bound). The open-loop phase and gain is often plotted versus frequency (Bode plot) to determine the gain and phase margin of a feedback system.