Infrared rays and ultraviolet rays are a part of the electromagnetic spectrum. These rays vary in their wavelength or frequency.
The frequency range of infrared rays varies from 1014 to 1012 Hz where as that of ultraviolet rays lies between 1016 to 1014 Hz
Infrared radiations are also known as heat radiations as they causes heating effect. They are low frequency radiations lying just below the visible light .
Ultraviolet rays lies just above the visible light. Short UV radiations are harmful to living tissues but these are absorbed by the ozone layer. Infrared radiations are used for long distant photography,in detection of enemy concentration , examining old paintings and detection of forgery of old paintings etc.
UV radiations are used as sterilizers,UV of lower frequencies are useful in the synthesis of vitamin D.