evidence: An international airport is an airport with customs and border control facilities enabling passengers to travel between countries around the world. International airports are usually larger than domestic airports, and feature longer runways and have facilities to accommodate heavier aircraft such as the Boeing 747 and the Airbus A380 commonly used for international and intercontinental travel. International airports often host domestic flights, which helps feed both passengers and cargo into international ones (and vice versa). [...] Most international airports feature a "sterile lounge", an area after security checkpoints within which passengers are free to move without further security checks. This area can have services such as duty-free shops that sell goods that have been selected and screened with safety in mind, so that purchasing and bringing them on board flights poses no security risks. In addition to employees, only processed passengers with a valid ticket are allowed inside the sterile lounge. Admittance into the sterile area is done in centralized security checkpoints in contrast to e.g. individual checkpoints at each gate. This allows for more efficient processing of passengers with fewer staff, as well as makes it possible to detect both delays and security threats well ahead of boarding.[24]