# Statistical Mechanics/The Foundations/Definitions

So, how do we define temperature? Pressure?

Extensive parameters are given with the problem, but these Intensive parameters have a much deeper meaning that gives truth to the reasoning of why we separate between extensive and intensive parameters. So, without further ado:

T = (∂U/∂S)_{V,N}

P = -(∂U/∂V)_{S,N}

μ = (∂U/∂N)_{S,V}