There are a variety, so your choice depends upon your budget and needs. A split system is the most popular choice. It has an indoor and outdoor unit and is connected by pipes containing refrigerant gas. They are ideal for single rooms or an open plan area up to around 60m². Multi-split systems have outdoor unit connected to two or more indoor units. They are ideal for two or three rooms that are reasonably close together, especially when separate split systems or a ducted system aren’t suitable.
Ducted systems have a discreet central unit, usually located in the roof that is connected by air ducts to air outlets and sensors in each room. It is ideal for larger houses or offices. A wall/window unit is installed in a window or through an external wall. These are good for rooms and open-plan areas of up to 50m². Smaller units can be plugged into a normal power point, while larger ones may need additional wiring. They’re not quite as efficient or effective as split-systems, but a reasonable budget option if a split system isn’t an option. Portable units are single units that can be moved from room to room as needed. Most have a flexible duct that must be attached to a window to vent the heat outside. They are not as efficient as split systems but they may be a good option if you are renting.