Auxiliary-field quantum Monte Carlo with the phaseless constraint (ph-AFQMC) is one of the leading candidates for ground state energy calculations for materials and molecules of moderate scale. This method corresponds with efficiently simulating an imaginary time evolution on a manifold of single Slater determinants. In this chalk talk, I will build up the theory of ph-AFQMC assuming no background in quantum mechanics or Monte Carlo methods. I will explain how it works, why it is efficient, and demonstrate why the phaseless constraint is necessary. If time permits, I will also briefly show how to download and use the SAFIRE library (safire.flatironinstitute.org) for doing AFQMC calculations on your own.