Condensation
Condensation is a physical phenomenon where water vapor (gas) changes into a more condensed state, either solid (frost) or liquid. This usually happens on windows when warm indoor air comes into contact with a cold surface, leading to condensation. It also occurs in poorly ventilated environments like bathrooms, where water vapor settles on glass surfaces.
Condensation on walls can be a sign of excess humidity, which can lead to health and property issues. To prevent these problems, using a dehumidifier is highly recommended: