Airport Check-in are service counters found at commercial airports handling commercial air travel.

The check-in is normally handled by an airline or a handling agent working on behalf of an airline. Passengers usually hand over any baggage they do not wish or are not allowed to carry-on to the aircraft's cabin and receive a boarding card before they can proceed to board their aircraft.

Check-in is usually the first procedure for a passenger when arriving at an airport, as airline regulations require passengers check-in by certain times prior to the departure of a flight. This duration spans from 30 minutes to over 3 hours depending on the destination and airline. During this process, the passenger has the ability to ask for special accommodations such as seating preferences, inquire about flight or destination information, make changes to reservations, accumulate Frequent flyer program miles, or pay for upgrades.

The airline check-in's main function, however, is to accept luggage that is to go in the aircraft's cargo hold.

Check-in procedures vary per airline with some airlines allowing certain restrictions other airlines have in place, and occasionally the same airline at two separate airports may have different check-in procedures. Such differences are usually not noted by the average passenger and occasionally leads to service interruption when one carrier refuses to abide by the procedure another carrier normally would be willing to do.