The book presents a modern understanding of combustion and reducing the flammability of polyolefins by modifying various fire retardants, and methods of evaluating flammability of modified polymeric materials.All methods to reduce the flammability of polymers are based on the following principles: a) a change in the thermal balance of the flame due to the increase in various kinds of heat losses; b) reduction of the heat flux from the flame to the polymer due to the creation of protective layers, such as formed coke; c) reduction of the gasification rate of the polymer and d) a change in the ratio of combustible and non-combustible decomposition products material in favor of non-combustible. As flame retardants metal oxides and hydroxide, halogen, phosphorus and silica containing compounds, expandable graphite, nano clays and other modificators are described.