IP stands for "Ingress Protection" and is a value used to rate and classify the degree of protection provided against the penetration of solid objects, dust, or water entering the light fitting.
It consists of 2 digits:
The first digit indicates the level of protection against solid objects or parts
The second digit indicates the level of protection against water
Selecting the proper IP rating should be reflected by the conditions on where the luminaire will be used or installed. Low IP ratings can be suitable for indoor use, such as residential and commercial areas. High IP ratings are suitable for outdoor use, showers, industrial areas, and locations with exposure to lots of dust or water.