Airport check-in

[1] During this process, the passenger often has the ability to ask for special accommodations such as seating preferences, inquire about flight or destination information, 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 and issue boarding passes.

This includes tickets, passports, visas, letters of consent, and in some cases, passengers' address and contact details to comply with immigration requirements.

Anything that is above the weight limit or which is not allowed to be carried by the passenger themselves in the aircraft cabin is usually handed over to the agent at the time of check-in.

Many airlines use electronic check-in such as ePass, mPass, or similar mobile apps, and these applications serve as the boarding pass.

Electronic bag tags are designed to streamline the baggage check-in process, allowing passengers to pre-tag their luggage from anywhere before arriving at the airport.

Online check-in is the process in which passengers confirm their presence on a flight via the Internet and typically print their own boarding passes.

Depending on the carrier and the specific flight, passengers may also enter details such as meal options and baggage quantities and select their preferred seating.

Some airlines, however, would still require passengers to proceed to a check-in counter at the airport, regardless of preferred check-in method, for document verification (e.g., to travel to countries where a visa is required, or to ensure the credit card used to purchase is genuine and/or matches the identity of the person who made the purchase).

Airlines may use the system because self-service is frequently more efficient to operate, with a greater ability to cope with surges in passenger numbers.

Some airlines charge for the privilege of early check-in before the 24-hour window opens, thus capitalising on the demand for desirable seats such as those immediately behind a bulkhead or emergency exit row, such as Ryanair, which allow check-in up to 60 days before the flight for passengers who pay for a seat reservation.

If the passenger carries a first or business class ticket or presents a certain frequent flyer program membership card (usually the higher-level tiers), or any other arrangements with the carrier, access to the premium check-in area and/or the lounge may be offered.

For example, Air New Zealand's Auckland International premium check-in lounge provides a dedicated customs clearance counter and direct shortcut access to the security checkpoints.

In some cities (including Dubai, Sharjah, Hong Kong, Kuala Lumpur, New Delhi, Chennai, Seoul, Vienna and Taipei), certain airlines provide in-town check-in services, allowing passengers to check their luggage at check-in counters located in railway or subway terminals as much as a day ahead of time.