Infra Red light is a light that the human eye cannot see but the monochrome CCTV camera can. Near Infra Red light is light of a longer wavelength than the visible spectrum, between 700 and 1,100nm, just beyond the visible spectrum. It is this near Infra Red that is used for CCTV purposes.
As Infra Red contains none of the colours visible to humans it cannot be used with colour cameras. To see Infra Red, monochrome or day-night cameras, are needed. CCTV cameras using Infra Red always provide monochrome images.
Infra Red light provides greater distance, a varying degree of invisibility (depending on the exact wavelength) and no light pollution.
Applications that require covert surveillance, or applications where even low levels of overt lighting must be avoided for reasons of light pollution, are ideal for Infra Red lighting.