Airport (G)

The Biggest Airport in the World
Taken literally as the airport which takes up the most land mass, this is the King Fahd International Airport in Damman, Saudi Arabia. It takes up some 780 square kilometres - an area larger than many cities.
By comparison, London Heathrow takes up around 3,000 acres, or just 4.7 square miles.
The Busiest Airport in the World
This depends on whether you monitor aircraft movements (the numbers of take-offs and landings), or passenger numbers. An airport such as Washington National may have relatively high aircraft movements, but as the largest aircraft it handles is a Boeing 757, it handles relatively fewer annual passengers than other airports with similar movements.Movements and passenger numbers are both acceptable methods of determining the "busiest" airport, although passenger numbers is the generally quoted figure.Most Passenger numbersAtlanta Hartsfield Jackson is the busiest airport in the world, handling 89 million passengers in 2010. Beijing Capital is the world’s second busiest airport (74 millions passengers in 2010), with former top dog Chicago O'Hare coming in third with 67 million passengers in 2010.
Busiest International Airport
London Heathrow handles the most international passengers (as opposed to passengers on domestic flights, which make up the majority of traffic at US airports). Heathrow carried 61 million international passengers in 2008, beating Paris Charles de Gaulle (56 million international passengers) and Amsterdam Schiphol (47 million international passengers) into second and third place respectively.
Busiest City (all airports)
When the flights from all airports in a city are combined, London is by far the busiest aviation centre in the world. Around 130 million passengers pass through London’s airports each year. Second placed Tokyo handles a mere 100 million passengers annually.
Only London, Tokyo and NewYork have two airports in the top 30 worldwide.
Source: Airport Council International
http://www.flightmapping.com/news/coventry-airport/biggest-busiest-airports.asp