Final answer:
Ultraviolet (UV) radiation refers to the electromagnetic radiation with wavelengths between 10 and 400 nanometers, which lies just outside the visible light spectrum toward higher energies. This high-frequency radiation forms part of the electromagnetic spectrum and has uses and risks for humans.
Step-by-step explanation:
The electromagnetic radiation that is just outside the visible range toward higher energy is known as ultraviolet (UV) radiation. This type of electromagnetic radiation has wavelengths that range from 10 to 400 nanometers, which are shorter than the shortest visible wavelengths. Within the electromagnetic spectrum, which includes all forms of electromagnetic radiation, UV rays have higher frequencies than violet light; hence the term 'ultraviolet' means 'beyond violet'. UV radiation overlaps with the lowest X-ray frequencies at its higher energy end.
While visible light occupies a narrow band of this spectrum, UV radiation lies directly above it. It is a high-frequency radiation that can cause effects such as sunburn and may potentially lead to skin cancer with enough exposure. Despite the dangers, UV radiation also has beneficial applications, including the synthesis of Vitamin D in the human body.