Researching burning rate of combustible substances in uncontrolled conditions during a fire is an ongoing task for the scientific community. Detecting and understanding phases of a fire on the molecular level first began by the end of the 1940s. However, it took a long time before we were able to define the processes that occur during combustion. The processes significantly affect further development of fires and their consequences. They are so important that they even affect the decision as to what methods and tactical approaches are chosen to extinguish fires - a decision that lies in the hands of firefighters. As the phases of burning and burning phenomena were being discovered and defined, we sought to find the safest and most adequate ways of extinguishing fires. It cannot be left to time and experience for firefighters to learn to recognize the phases of a fire. For this reason training in firefighter training simulators is essential. The simulators are container-type structures that differ in the type of fuel used for combustion and fire simulation. Safety and protection of firefighters from flammable shocks in already described indoor burning processes is also the theme of this final work. What distinguishes this thesis from similar ones is the fact that it contains my personal experiences acquired over the years working as a firefighter and through successfully finished training programs.