Refresh rate does not apply to LCD monitors becuase of the difference in operation between LCD and CRT monitors. LCD monitors still have a refresh rate property becuase it would have cost too much money to replace it with something else, since our graphics cards are designed to operate with a refresh rate.

Anyways, for more information, check out the Wikipedia entry:

https://en.wikipedia.org/wiki/Refresh_rate

In LCD monitors, I think (don't try it at home, I'm not 100% sure) that if setting a refresh rate higher than what is supported won't fry your screen becuase of built in protection, unlike CRT monitors where the refresh rate controls the electron gun.