An air conditioner is a device that cools and dehumidifies the air in a room or building. It works by removing heat from the indoor air and transferring it outside, making the space more comfortable during hot weather. Most air conditioners use a refrigerant, a special fluid that absorbs heat, to help with this process. In addition to cooling, air conditioners can also improve indoor air quality by filtering out dust, pollen, and other allergens. Many modern units come with programmable settings, allowing users to control the temperature and energy usage easily, making them both convenient and efficient for everyday use.