An "outdoor unit" typically refers to a component of a heating, ventilation, and air conditioning HVAC system. It is located outside a building and works in conjunction with an indoor unit to regulate indoor temperatures. The outdoor unit contains essential parts like the compressor, condenser coil, and fan, which help dissipate heat from the indoor air. In air conditioning systems, the outdoor unit absorbs heat from inside the building and releases it outside. In heat pump systems, it can also extract heat from the outside air to warm the interior during colder months. Proper installation and maintenance of the outdoor unit are crucial for efficient operation.