An AC (or air conditioner) cools every household room. To understand how an actual aircon works, you must compare it to a refrigerator as both appliances function in the same manner. An air con functions by gathering warm air from a room, passing them through its cooling coils and eventually releasing the back in the room with a cold breeze. The cooling coil possesses a liquid substance which then warms up as it is being pumped to the outward-facing side of the air con. The air then passes through a new set of coils which interacts with the air outside. It eventually sends the hot air at the back of the air conditioning unit.
Air conditioners come in different sizes. An important consideration is to identify what type of unit is suitable to your room. Buying a large air con will cost you a lot of money since electricity for this will be quite heavy. If you are planning on buying a small air conditioner for a large living room, then it is probably not a recommended decision as it will not cool the room ideally. Nowadays, there are other units which have advanced features such as a digital screen, a timer setting, different fan speeds and a customizable thermostat.