Humidification is the process of adding moisture to air

Humidifiers help your skin stay hydrated and supple. In the winter time when the air is colder and drier, skin can’t hold onto as much moisture as it can with warm air. You need to supplement [moisture] because when it gets dry enough, the moisture on our skin evaporates into the air. This is particularly important in the winter. Any way you can add humidity to the air in an environment in which you spend a lot of time is going to be helpful.

Humidifiers infuse the air with moisture, soothing dried out, itchy, cracked skin. 

Humidification is the process of adding moisture to air, it involves spraying Water (as in Evaporator coolers) or even spraying hot steam (so as to additionally increase the temperature of air) in the Air mixture. Humidifier is the Device that is used to accomplish this task....
Descriptively, Ambient air is a mixture of two components, dry air and water vapor.