An aircraft carrier is a large ocean-going ship designed to transport aircraft, which can then use the deck of the aircraft carrier to take off. Using aircraft carriers conserves jet fuel, and also allows a military a bigger flying range, by bringing the aircraft closer to the area of interest. Many bombers and jets actually have very short ranges, which can make it difficult to launch a practical offensive on a target. The crew who staff an aircraft carrier work together a closely coordinated team to launch planes during combat and provide a base of operations for military staff.
Aircraft carriers take advantage of a convention of international law that ships in international waters act like sovereign entities. As long as an aircraft carrier stays clear of claimed coastal waters, it can be run like a branch of its home nation. Several countries including the United States keep aircraft carriers on strategic standby, prepared to sail to the site of a conflict at all times. While aircraft carriers are not particularly speedy, they are incredibly sturdy and staffed by highly trained crew who essentially turn them into mobile battle command centers.
An aircraft carrier includes a deck with a runway, and a hangar below with storage for additional planes and equipment, reachable by giant elevators which can bring planes to the upper deck. The carrier also has a command tower, along with quarters and amenities for large numbers of staff. Hundreds of people live and work aboard aircraft carriers, ranging from pilots to gallery staff, and they may be deployed together for months at a time.
The runway of an aircraft carrier, while long, is nowhere near as long as land-based runways. If a pilot overshoots the deck or does not get enough lift during takeoff, the aircraft will end up in the ocean. Piloting planes on and off an aircraft carrier is a very skilled task, and the most highly trained pilots work on aircraft carriers. Takeoff is difficult: in many cases, pilots actually have to be launched using giant catapults, because the runway is too short for the plane to build up enough speed to take off. Landing is also challenging: pilots must hit the deck at just the right angle and at a safe rate of speed, catching the tailhook of the aircraft on arresting wires stretched across the deck, which will prevent the plane from crashing into other aircraft on board, or the ocean.
Working on an aircraft carrier is extremely dangerous: aircraft can catch fire, or blow personnel overboard with their powerful engines. As a result, aircraft carriers are stocked with safety equipment like fire retardants, fire trucks, and safety nets. The work environment is also extremely noisy, requiring crew to wear ear protection and communicate with hand signals and radios. Most staff wear protective gear as well, including head helmets and inflatable vests.