This book presents a guide to the optimal power flow and dispatching literature from early 1930?s to present. It classifies the methods in some detail according to the optimization techniques used and shows the functional and chronological relationships. It is not a critical review in that it does not asses the various techniques. It is concluded however that there has been a marked progression in the network modeling, optimization and numerical techniques over the years. Today, commercially available OPF algorithm all satisfy the full nonlinear load flow model and a full set of bounds on variables. Some have incorporated contingency-security constraints and in future might include the discrete operation of certain variable. Most new OPF algorithms are new based on Newton methods and feature the fast-decoupled network model in their sub-problems, resulting in superior convergence characteristics.