In the wild, the sun heats your reptile's natural habitat, which in turn warms your reptile's blood, and allows them to digest their food better, and in captivity it is important to simulate this, usually using a HabiStat Heat Mat.
 
A gentle way to heat your reptile's environment rather than heat bulbs, these heat mats use Ultra Long Wavelength Infrared emitted from the printed carbon.
 
Heat mats do get warm but provide a very gentle warmth which the reptile can sit under or on top of. Used under normal conditions the mats cannot burn the animal.
 
It should be noted that heat mats give a gentle background heat. If you are keeping animals that requires higher temperatures, then you may require additional supplemental heating.