The slang name for what is used in Infrared security cameras the 'stealth factor'.
Having an infrared Security camera is something that should be considered as many people know that burglars and intruders typically will do their jobs being concealed in the darkness. Most thieves do not take into consideration that the target could or will have an infrared security system installed. Using the infrared security camera systems you will be able to catch the thieves red handed.
One important feature you should be sure to have included when you are purchasing is the auto scan functionality. This way the camera will move back and forth at the speed you set making it harder for the thief to hide from it.
Many infrared cameras use beams which send light out, you can imagine a flashlight, it points that sort of beam. The main difference between a flashlight and the infrared security camera beam is that you will not see the light.
Do not confuse low light security cameras with infrared security cameras. The low light security camera does not utilize the infrared technologies.
If you have a large area you need monitored, you will need to install many infrared security cameras. The infrared security cameras do not cover large areas of space.