The basic variants of evolution strategies, a special instance of evolutionary algorithms, are discussed in this paper. Gleaned from the model of organic evolution, evolution strategies are characterized by the additional self-adaptive process that fine-tunes their strategy parameters during optimization. This property is a fundamental ingredient for the application to challenging engineering applications involving resource-intensive simulation runs. For one instance of such applications, the single-criterion and multi-criterion airfoil design problem, the results of an evolution strategy are presented and discussed in this paper.