Power system dispatch is a general concept with a wide range of applications. It is a special category of optimization problems that determine the operation pattern of the power system, resulting in a huge influence on the power system security, efficiency, and economics. In this paper, the power system dispatch problem is revisited from the basis. This paper provides a categorization of the dispatch problem, especially with an emphasis on industrial applications. Then, this paper presents a detailed review of the dispatch models. The common formulations of the dispatch problem are provided. Finally, this paper discusses the solutions of the dispatch problem and lists the major challenges.