what does the gain margin and phase margin of a particular circuit or configuration tell us...........
what role does the gain margin and phase margin play in designing of circuits .........
in simple explain the importance of gain margin and phase margin
GM and PM are the measures of a feed back system that tells us what max allowable variation (ie., "margin") we have at hand without pushing the system into instability.
Feedback Control System by BC Kuo is worth reading.
In addition to what mentioned before ,the importance of the phase and gain margins that they give a quantitative measure for the stability of the feedback system rather than stating that the system is just stable or unstable.
The stabilty of your feedback system depends on the phase and gain margin. The analysis fof the same can be done byusing Bode plots or Root Locus plots.