IP Protection
Any outdoor luminaires you want to install in your bathroom or garden must be waterproof. IP stands for Ingress Protection, meaning nothing can get in. Exactly that is what the IP protection class states. It indicates the degree of waterproofing of a luminaire.
The IP code always has two digits. The first digit describes the degree of protection against foreign bodies and direct contact, while the second digit describes the degree of protection against water and moisture in general.