All materials oscillate (or, vibrate) at a sub-atomic level and the oscillating electric field generates an oscillating magnetic field, the magnetic field in turn generates an oscillating electric field, and so on.
These oscillating fields together form an electromagnetic wave. Electromagnetic (EM) radiation is a self-propagating wave in space with electric and magnetic components and is classified into types according to the frequency of the wave: these types include, in order of increasing frequency, radio waves, microwaves, terahertz radiation, infrared radiation, visible light, ultraviolet radiation, X-rays and gamma rays.
From the picture above you can see how the different types relate to one another. The Sun’s radiation includes short wave radiation through the visible part of the spectrum through to microwave and radio frequency. The UV radiation lies beyond one end of the visible part of the spectrum and Infra Red (IR) beyond the other end.
Infra Red radiation has no visible nor UV content, it is purely heat. In contrast, an incandescent light bulb emits less than 5% of it’s energy as light with the remaining 95% as heat (in the IR part of the spectrum). An energy saving fluorescent tube emits much more of it’s energy as light so produces less heat. The amount of light vs. heat depends upon the particular design. Some of the radiation from a fluorescent tube is at and beyond the blue part of the visible range to confer a ‘cool’ colour characteristic.
If you would like to know more about Electromagnetic (EM) radiation visit the Wikipedia website by clicking on this link: Wiki Electromagnetic radiation