This chapter presents the motivation for the development of the present book. Because the need for electricity is pervasive in our society, there is a continuing interest in the technology of electric power production and distribution. The chapter presents some forecasts of electric power production that indicate the massive use of thermal power plants, fired with coal or natural gas. In order to improve the efficiency of those power plants, the use of Overall Equipment Effectiveness (OEE) as a key performance indicator is discussed. Finally the link between reliability and maintainability concepts and the OEE index is presented.