Why is luminescence often called cold light?

Luminescence is often referred to as "cold light" because the emission of light does not result from the material being heated to high temperatures.1

Unlike incandescence—where light is produced by heating bodies such as burning wood, coal, or wire—luminescent materials emit light while remaining relatively cool. In these processes, the material absorbs energy from sources like radiation or chemical reactions, which excites its atoms. As the atoms return to their unexcited ground state, they release the absorbed energy as light. Because this conversion of energy into visible light occurs without the significant generation of heat associated with thermal emission, the term "cold light" is used to describe the phenomenon.123