Infrared radiation (IR) is a type of electromagnetic radiation that exists between visible light and radio waves. It has wavelengths ranging from about 700 nanometers to 1 millimeter, which are longer than visible light waves but shorter than radio waves. IR is commonly divided into near-, mid-, and far-infrared, and can be further divided into five categories: near-infrared, short-wavelength infrared, mid-infrared, long-wavelength infrared, and far-infrared. IR radiation is one of the three ways heat is transferred from one place to another, and all objects with a temperature above around 5 degrees Kelvin emit IR radiation. IR has a variety of uses and applications, including heat sensors, thermal imaging, night vision equipment, and sensing and detection. In networking, wired and wireless operations use infrared light, and remote controls use IR radiation. In the medical field, interventional radiology (IR) is the use of medical imaging techniques to guide doctors as they diagnose and treat certain conditions.