This chapter reviews the applications of intumescence in the field of fire protection(resistance to fire) and fire retardancy (reaction to fire) of material. It startsdescribing the basics of intumescence and gives the main intumescent productsavailable on the market associated with their typical application’s fields. It coversthe reaction to fire of intumescent polymers and textiles including the latestdevelopments of flame retardants as well as synergists. Resistance to fire is alsoconsidered using intumescent coating at the large and reduced scale. Mechanismsof action are always discussed considering the chemical, physical and thermalaspects.