Thermal radiations are commonly referred to as infrared radiation, heat radiation, or thermal energy. Infrared radiation is a type of electromagnetic radiation that cannot be seen by the naked eye but can be felt as heat. Heat radiation is the process of transferring heat energy through the emission of electromagnetic waves. Thermal energy refers to the amount of heat present in a system. Synonyms of thermal radiations vary depending on the context, but they all imply the transfer of heat through radiation. Other synonyms include IR radiation, thermal emission, thermal radiation, and radiant heat.