At a busy airport like Atlanta's Hartsfield International, 2,500 flights take off and land every day. That means that, each day, perhaps as many as 250,000 people move through the airport and need certain services. Airports provide those services in their concourses and terminals, the heart of any airport. There you'll find the space for airlines to handle ticket sales, passenger check-in, baggage handling and claims.
Terminals come in many sizes and designs. At small airports, a single building holds a common ticketing and waiting area with several exits -- or gates -- leading to aprons, where aircraft park and boarding takes place. At large airports, this basic design can be expanded, which results in a linear or curvilinear terminal, often a very long building with plenty of room to accommodate ticketing and check-in and multiple gates for access to aircraft. In the 1950s, the linear concept evolved into the pier-finger terminal. In this configuration, passengers are processed in the main terminal and then directed down one of several piers, where aircraft await in gates known as finger slots. Concourses, the open areas formed where the main terminal building and the various piers meet, provide spaces for shops, restaurants and lounges.
The terminal complex at Atlanta's Hartsfield airport covers 130 acres -- that's 5.7 million square feet (529,547 square meters) of space available to handle all of the necessary aviation activities! The complex includes the domestic and international terminals and seven concourses. Within these concourses, there are 114 food and beverage vendors (most of these are owned and staffed by private companies), 90 retail and convenience stores (also owned and staffed privately) and 56 staffed service outlets (places where you can get your shoes shined or connect to the Internet) [source: Hartsfield-Jackson].
Hartsfield's concourses also lead to the gates. There are 207 gates in all (167 domestic and 40 international) [source: Hartsfield-Jackson]. The gates are where the airplanes park for passenger boarding and deplaning. Passengers wait in the immediate area of each gate to board the plane. Gates are rented by each airline from the airport authority, and some airlines may rent a whole terminal building in their "hub" airport, in which case the rental fee alone can run into the millions of dollars.
Routine airplane maintenance, such as washing, deicing and refueling, is done by airline personnel while the plane is parked at the gate. In some cases, other maintenance tasks might be performed at the gate, possibly with passengers onboard the plane – it's not uncommon to sit on a plane at the gate while maintenance personnel replace something like a hydraulic brake line on an aircraft.