1. Hartsfield-Jackson Atlanta International Airport (ATL)
    The Atlanta International Airport has been number one among the busiest airports in the world since 1998. It serves 252,000 passengers each day.
  2. Beijing Capital International Airport (PEK)
    Located 20 miles outside of Beijing’s city center, Beijing Capital International Airport quickly climbed the rankings of the world’s largest airports, becoming the busiest in Asia and the second on this worldwide list.
  3. London Heathrow Airport (LHR)
    Heathrow is the busiest airport in the UK and serves more international passengers than any other airport in the world.
  4. Tokyo International Airport (HND)
    This Tokyo airport, also known as Haneda Airport, handles most of Tokyo’s domestic flights and few international flights.
  5. O’Hare International Airport (ORD)
    O’Hare, a mega-airport located in Chicago, Illinois, offers flights to more than 60 international locations. It is number two on the list of the world’s biggest airports according to number of aircraft movements.
  6. Los Angeles International Airport (LAX)
    As the busiest airport on the West Coast of the U.S., Los Angeles International, also known as LAX, earned the nickname the “Gateway to the Pacific Rim.”
  7. Paris Charles de Gaulle International Airport (CDG)
    Charles de Gaulle, also known as Roissy Airport, is located to the northeast of Paris and is the main hub of Air France.
  8. Dallas/Fort Worth International Airport (DFW)
    DFW is considered an airport city because it includes on-airport businesses, such as retail and a hotel. In June 2013, the Dallas/Fort Worth Airport will reach a total of 200 destinations offered to its passengers and join an elite group of airports with this distinction.
  9. Soekarno-Hatta International Airport (CGK)
    The Soekarno-Hatta Airport, located outside of Jakarta, Indonesia, is currently being expanded to serve a growing number of passengers.
  10. Dubai International Airport (DXB)
    This Dubai airport is one of the main airline hubs in the Middle East and serves every continent excluding Antarctica.
  11. Frankfurt am Main Airport (FRA)
    The Frankfurt Airport is the busiest in Germany and offers the largest number of international destinations in the world.
  12. Hong Kong International Airport (HKG)
    This airport has been operating since 1998 on the small island of Chek Lap Kok.
  13. Denver International Airport (DEN)
    The Denver International Airport is the largest in the U.S. by area and the second largest in the world.
  14. Suvarnabhumi Airport (BKK)
    The Suvarnabhumi Airport, also known as New Bangkok International Airport, is located 16 miles from downtown Bangkok.
  15. Singapore Changi Airport (SIN)
    The Changi Airport serves over 100 airlines and is the home base of 8 major airlines in Southeast Asia.
  16. Amsterdam Airport Schiphol (AMS)
    The Schiphol Airport occupies 3,200 acres and is considered an airport city.
  17. John F. Kennedy International Airport (JFK)
    This airport, formerly known as Idlewild Airport, is located in New York City. It is just one part of the New York City airport system which is the largest in the U.S. and the second largest in the world in terms of travelers served.
  18. Guangzhou Baiyun International Airport (CAN)
    This airport is located in the Guangdong province of China. It is China’s second busiest airport.
  19. Madrid Barajas Airport (MAD)
    The Madrid Barajas is Spain’s main international airport. Established in 1928, it has now expanded to become one of the most valuable aviation centers in all of Europe.
  20. Ataturk International Airport (IST)
    This airport was named in honor of the founder of the Republic of Turkey. In 2013, Ataturk International Airport was named Airport of the Year and voted Europe’s Best Airport.

Source: http://blog.flights.com/worlds-biggest-airports.html