The term "checked baggage" refers to luggage that is stowed in the belly of an aircraft during flight. Passengers will leave luggage with airline personnel so it can be stowed during flight; this prevents overcrowding within the cabin of the plane. It differs from carry-on baggage, which is any piece of luggage that is carried into the cabin of the airplane for storage in overhead bins or underneath seats. Checked baggage limitations can vary, and many airlines now charge passengers to check a bag onto a flight.
Most airlines require that checked baggage be under a certain weight or size. If the luggage is larger or heavier than the outlined regulations, the passenger will be subject to extra fees. In the past, airlines did not charge a fee for bags that fit under the weight and size regulations, but more and more airlines have changed their policies to include fees for checked baggage; many still offer checked bag services free of charge, while others offer free services for one bag only. Fees apply for baggage checked beyond the first bag.
A passenger will check his or her luggage at a check-in counter at an airport. Once the bags are checked, they will be tagged with the passenger's flight information so the bags can be transferred if the passenger has a connecting flight. The bags will be loaded into storage compartments in the belly of an airplane by baggage handlers. Once inside the belly of the plane, the bags will be stacked and secured so they do not shift during flight. Passengers will not be able to access checked baggage during flight or at a connecting stop. Once the passenger reaches his or her final destination, the luggage will be loaded onto a conveyor system that runs into the baggage claim area within an airport so the bags can be claimed.
Another type of checked baggage is gate-check baggage. This occurs when the overhead compartments within an aircraft fill up, but oncoming passengers still have luggage to stow. Flight attendants will ask passengers to tag their bags and leave them at the gate so a baggage attendant can load the bags into the storage area in the belly of the plane. When a bag is gate-checked, the passenger will not be charged for checking the bag. In some cases, the stowed baggage will be unloaded at the gate when the plane arrives at the airport so passengers can have their carry-on items for another flight.