Infrared heaters are radiant heaters which heat objects, materials or living spaces by projecting invisible infrared light. Infrared light waves emitted from infrared heaters create radiant heat which warms, cooks or dries similarly to UV light; however, infrared heaters use electromagnetic radiation rather than light waves to transmit heat energy. Infrared heat waves are long electromagnetic waves located very near the visible part of the electromagnetic spectrum. Because infrared heat does not depend on light waves or forced air to be transferred, infrared heat can penetrate materials and gases more easily than typical convection heaters or even UV lamps. Infrared heaters may be radiant gas heaters which create heat from gas-fired flames, or they may be electric infrared heaters, also known as quartz heaters. Gas-fired infrared heaters are used for larger, more industrial applications such as shed heaters, outdoor heaters, garage heaters, and overhead door heaters, while electric infrared heaters are typically used in as infrared space heaters, infrared patio heaters and other comfort applications. Both gas and electric infrared heaters are commonly configured as tube heaters, and the projected infrared waves are directed and/or concentrated by a series of reflectors, reducing wasted energy.

Infrared heaters are best used in areas where objects and materials require drying or heating, rather than the air within a space. Adhesive curing, drying lacquer, liquid paint curing and powder coat curing is often accomplished by infrared heaters, which cure 3 dimensional objects more thoroughly using less energy than regular convection heaters.

Electric and gas-fired infrared radiant heaters have different heat emitting bodies, or heat creating sources, although both types may contain the heat emitting element within a radiating tube; infrared heaters which use filaments or heat sources within glass tubes are known generally as tube heaters. Electric infrared heaters are powered by an electrically heated tungsten wire filament encased in a heat-resistant quartz glass tube; for this reason, electric infrared heaters are also called quartz heaters. Gas-fired radiant heaters, which are usually tube heaters, convert the heat energy created by the gas flame into infrared electromagnetic radiation through filaments, tubes or ceramic heat exchangers combined with a series of reflectors. Some radiant heaters may combine fans and air movement with infrared heat to redistribute heated air molecules and spread heat around a room faster, but these are not necessary for efficient infrared heating.