Stochastic programs are mathematical programs that involve data that is not known with certainty. Deterministic programs are formulated with fixed parameters, whereas real world problems frequently include some uncertain parameters. Often these uncertain parameters follow a probability distribution that is known or can be estimated. Thus stochastic programs approximate unknown data by probability distributions. The goal is to find some policy that is feasible for all (or almost all) the possible data instances and that maximizes the expectation of some function of the decision variables and the random variables.