The graph shows that as the temperature of the hot body increases, the peak energy it emits shifts towards the shorter wavelength.
As the temperature increases, the wavelength of the emitted radiation can be detected by our eye and the waves are called light waves.
In this case the object appears red-hot and the waves lie in the red part of the visible spectrum.
If the temperature of the body is further increased, more wavelengths of the visible spectrum are produced and the object eventually becomes white-hot.
When radiation emitted from a white-hot filament is incident on a prism, the different components of the electromagnetic spectrum are split as shown. Using an infrared detector, the presence of infrared radiation can be detected above the region of red light.