1)  AC is the most widely used term that most people already know and of course it stands for Air Conditioning.  Air Conditioning was actually invented in 1902 by a man named who was working for a printing company named Willis Carrier.  

His original intent had nothing to do with providing comfort cooling to humans or refrigerating food, in fact his sole reason for this new invention was just to remove humidity from inside the printing plant where he currently worked.   

If you’ve ever worked at a printing plant or even passed through one for a few minutes you’ll understand exactly he did this. It was purely due to the Mother of Necessity that Willis Carrier dreamed up such a system.  Rooms were mass printing is produced are extremely humid to the point of extreme discomfort to the workers and other occupants. 

He accomplished this feat by blowing air through water cooled coils and because the coils were cooled to a temperature lower than the current dew-point it caused the  humidity to collect as droplets on the surface of the coil and run down into a pan below effectively removing the humidity from the working space air.  This is also widely known as de-humidification by refrigeration.