Along with traditional income and payroll taxes, airlines and their customers (passengers and shippers) pay many special taxes and fees to a variety of authorities, both at home and abroad. 
Among the stated purposes of these taxes and fees are homeland (national) security, environmental protection, disease control, infrastructure enhancement, airport and airway operations and maintenance, and agency financing.
Get a more in-depth review in The Taxation of Air Transportation, by Dr. Kenneth Button.
U.S. and foreign taxes have grown in number, amount, and scope since the advent of air transport. The amount a passenger pays in taxes and fees on a ticket varies according to his itinerary, including the number of times he or she boards a new flight and at what airports. For an illustration of domestic ticket tax scenarios, see below.
Foreign-levied aviation taxes are numerous and varied. The burden is exacerbated by tax "competition" between the U.S. and foreign governments, as well as local airport authorities, and has grown with the advent of post-Sept. 11 security fees. The most comprehensive and current source of tax information available is the IATA List of Ticket and Airport Taxes & Fees. Contact the International Air Transport Association (IATA) directly for pricing information.