Air conditioners, often abbreviated as ACs, are devices designed to regulate indoor air temperature, humidity, and overall air quality for comfort or for specialized purposes like preserving perishable goods in refrigerated environments. They are commonly used in residential, commercial, and industrial settings.

There are several types of air conditioners, including:

1. Central Air Conditioning Systems: These are common in larger buildings and homes. They consist of a central unit that cools and circulates air through ducts to various rooms.

2. Window Air Conditioners: These are self-contained units that are typically installed in windows or through-wall openings. They’re suitable for cooling individual rooms or small spaces.

3. Split Air Conditioners: These consist of two units—an indoor unit and an outdoor unit. The indoor unit contains the cooling coil, while the outdoor unit houses the compressor and condenser. They’re often more efficient and quieter than window units.

4. Portable Air Conditioners: These are freestanding units that can be moved from room to room. They typically vent hot air through a window or duct.

Air conditioners work by transferring heat from inside a building to the outside, thus cooling the indoor air. They use refrigerants, which circulate between the indoor and outdoor units, absorbing and releasing heat as they change from liquid to gas and back again.