This chapter presents the techniques for solving thermal radiation problems in various cases of engineering interest. First, elementary heat transfer cases of thermal radiation are studied, which are the cases of two black and grey isothermal parallel and infinite surfaces in a vacuum. In this first analysis, the technique of electrical analogy is presented to solve problems of thermal radiation. The concept of thermal radiation shape factors is introduced to solve more complex cases. Shape factors for various situations and geometries are presented next. From this theory, several cases of heat exchange by radiation are solved, starting with three enclosed surfaces and extending the solution to n surfaces forming a closed envelope. The concept of thermal radiation shielding is presented with illustrations of practical cases, such as temperature readings from a thermocouple. Chapter presents an analysis of the combined heat transfer of thermal radiation and convection. A black cavity modelling is also analized. Finally, the chapter concludes with subject of thermal radiation in gases.