Because you can photograph in the dark and through haze, this type of photography is useful for many things. These include scientific purposes, underground and smoke filled rescue operations, along with surveillance, aerial photography, victim locating, medicine, research and development, home inspections, military operations and intelligence.
Infrared photography and films produce images that aren't possible with conventional films. Infrared cameras are available, but you can usually use the same cameras, light sources and processing solutions as in normal photography. However, it is usually only used by skilled photographers, scientists and technicians who have a particular purpose or goal. Basically, infrared photography enables the film to capture and record what the eye cannot see as most materials reflect and transmit infrared radiation differently than visible light. You can also shoot hot radiation objects by the radiation that they emit. Digital camera sensors are generally sensitive to infrared and it interferes with normal photography, so it isn't practical with digital cameras.
Infrared photography will require you to do some research as there are various filters and flashes you can use and you will need to know how certain materials and types of light will affect your photographs.