Flame retardancy refers to the ability of a material to resist ignition and slow down the spread of fire. This property is crucial in various applications, such as in textiles, plastics, and building materials, to enhance safety and reduce fire hazards. Flame retardant chemicals are often added to these materials to improve their resistance to flames. The effectiveness of flame retardancy can be measured by specific tests that evaluate how well a material withstands heat and flames. Common flame retardant materials include brominated compounds, phosphorus-based additives, and chlorinated compounds. These substances work by either forming a protective char layer or releasing gases that inhibit combustion.