This paper, by using examples and theory, is trying to show the importance of using thermal insulation, i.e. resistance to the passage of heat, which can be used to achieve significant energy savings. The paper describes the historical development of thermal insulation from the very beginning, when earth was used for insulation, until today. The paper describes the most commonly used materials of natural and artificial origin. The materials that are being developed are also listed. The advantages and disadvantages of each material and the method of performing insulation with these materials are explained in more detail. When performing insulation, it is very important to know the properities and compatibility of materials in order to perform the insulation as well as possible. High-quality insulation reduces energy losses, lowers maintenance costs and increases the comfort of the stay. The paper is divided into several parts. The introduction, as the first unit, explains the importance of thermal insulation. The second unit leads historically through the development of materials and performance of insulation. The third unit is dedicated to getting to know some of the materials and their characteristics. The end of the pape ris dedicated to clarifying possible problems that may arise during the performance of exploitation of thermal insulation. The paper presents problems and possible solutions through three frequent examples.