Sample Variance different, someone, better, understand

LiquidAssets10

As I understand it... we have two formulas. One is for the "sample variance", and the other is for the "estimation of a population variance". (Correct me if I'm wrong here)

In the first one, we divide over "n". And in the second one, we divide over "n-1".

Can someone explain how the "n-1" gives a better estimation? This is very bizarre.. i don't see why do we treat the sample any different from the population.

Thanks guys!