When buying a light for outdoors or for the bathroom you need to check the IP (Ingress Protection) rating. The higher the rating, the more protected lighting is.
The first digit refers to the degree you’re protected from any contact with moving parts, and the degree the light is protected from anything getting inside. This ranges from ‘0’ (no special protection) to ‘6’ (dust tight).
The second digit indicates how much moisture (drips, spray or jets) the light can withstand. This ranges from ‘0’ (no special protection) to ‘8’ (protection from complete, continuous submersion in water). For example, an IP44 rating means nothing bigger than 1mm can get in, and it’s safe from splashing water.
For outdoor or bathroom lighting you need a minimum IP44 rating.