The mechanisms of heat transfer typical for technical applications are discussed in the introductory part. Further heat transfer of solids is discussed: differential equation of heat transfer, analytical and advanced numerical methods for solving the equations. Lectures include characterization of temperature dependent material properties, boundary conditions necessary for the determination of the task. Two lectures are devoted to inverse thermal problems and their importance for refining thermal computations. The closing lecture is focused on typical technical applications requiring the determination of unsteady temperature and tension fields, summarizing the knowledge of the given chapters, mechanisms of heat transfer, numerical solution of the thermal tasks and inverse computations.