English: Hot colors - the visible color of objects heated to incandescence. The spectrum of the thermal radiation depends on the temperature, so by observing the color of an incandescent object it is possible to determine its approximate temperature quickly and easily without high precision equipment. Before the invention of non-contact thermometers, observing the color was the only way to judge the temperature of hot objects, for example in forging metal. Simple abbreviation such as "red hot" and "white heat" are often used to describe these temperatures.