Any object or body whose temperature is above absolute zero emits electromagnetic radiations.
It means all of us emit electromagnetic radiations according to our body temperature. A cold object emits radiation of low frequency like microwaves or radio waves while the hotter object emits visible light, and other higher frequencies like ultraviolet and gamma rays.
Black Body Radiation
If a body is perfectly black it means that it absorbs all the incident light falling on its surface, When the light and other wavelengths come out from it is called the black body radiation.
You can very well estimate the temperature of flowing lava by looking at the colors of the lava. The temperature of the colors are represented below in the descending order
Sun as a black body
The energy emitted by the black-body is not shared equally by all the wavelengths of light. The spectrum of the black-body radiation shows that some wavelength has more energy than others. Let us look at the spectra of black body radiation at different temperatures:
The experimental facts: