There are two types of air conditioners, namely window and split air conditioners. A window unit is good enough for a single room or two rooms without a partition, whereas the split unit is advisable for more than a single or double room and much larger space.
Window unit can be mounted, as the term suggests, only on an open window or outlet. On the other hand, the split unit can be placed anywhere, even in a room without a window, since the main unit is placed elsewhere. The split unit is sleek and has the advantage of better cooling though with a slightly higher consumption of power than that of the window unit.
Split type systems are usually preferred because the noise of the unit is far away from the room where the outlets are kept. This is the main reason for their popularity.
The condensing unit and the compressor are kept in different places and ducts are used to bring the cool air to the room where the outlet is kept. This way only a very small place is occupied to keep the outlet unlike window unit, which takes up a large space to accommodate the cooling unit.