Radiation is a somewhat general term that can often refer to the energy emitted by nuclear chemical reactions or decay. You are specifically talking about thermal radiation, which is the electromagnetic radiation that is emitted from any object with thermal energy (in other words, any object that has heat). Five applications are listed below.
1. Cooking. Thermal heat given off from a heating element on an electric range is transferred to a pot or pan containing food.
2. Home heating. Thermal heat given off from hot water in pipes from a baseboard heating system is transferred to the air to heat a house in the winter.
3. Light. A traditional, incandescent light bulb with a filament converts electrical energy into heat energy which emits light in the visible spectrum.
4. Thermal imaging. Radiation is also given off in the infrared range of light that we cannot see but special cameras can be used to visualize this radiation. There are many military and security applications of this.
5. Photosynthesis. Radiation from the Sun is the ultimate source of energy on the surface of the Earth. Sunlight is used to plants to power photosynthesis, or the process where plants produce food.