A passenger airplane is an aircraft which has been designed and equipped to carry passengers, in contrast to a cargo airplane, an aircraft designed for cargo. Passenger airplanes have a number of features which make them uniquely suited to carrying humans, ranging from seating for passengers to pressurization systems which make the environment of the cabin safe for passengers.
There are two types of passenger airplanes: private aircraft, and commercial aircraft. Private aircraft are designed to be flown or chartered privately, and they are typically small, with a passenger capacity under 12. Commercial aircraft, by contrast, are used by airlines to haul large numbers of passengers. In addition to being bigger, commercial aircraft are also faster, and they have a longer range. Both tend to be rather expensive, although some private planes are quite affordable for aircraft hobbyists.
From a health and safety perspective, the critical difference between a cargo airplane and a passenger airplane is the use of a pressure and climate control system in a passenger aircraft. This system keeps the air in the cabin of the aircraft comfortable, and prevents rapid depressurization, which can be deadly. Passenger airplanes also have air purification and recirculation systems which provide passengers with oxygen to breathe. Without these measures, the cabin of an airplane would be inhospitable once the plane reached altitude. Some private aircraft lack climate and pressure control, and are therefore only suited to low altitude flights.
In addition to design features which keep the passengers alive, a passenger airplane also has features which keep passengers comfortable, starting with seating. Commercial aircraft usually include restrooms, and some also have a galley area in which food and drinks can be prepared. Larger commercial aircraft usually also have entertainment systems which allow passengers to listen to music, watch films, and engage in other activities while the passenger airplane is in flight.
Commercial airliners are classically divided into various classes or cabins, with varying degrees of luxury. Tourist, economy, or third class has only the most basic amenities, while business or second class is more comfortable. First or luxury class on a passenger airplane may include features like chairs which recline into beds for long haul flights, real china at food service rather than plastic trays, and services such as massage and manicures for weary passengers.