What Is An Ir Illuminator?

http://www.securitycamerasdirect.com/browse/categories/accessories/infrared-illuminators/ - An IR illuminator is used by security cameras to help them see in the dark or in low lighting levels. An infrared illuminator is like a night vision goggle, only of better quality. Without infrared illuminators, security becomes non-existent as soon as it gets dark. This is why most security cameras now come with IR illuminators.