Online check-in is a digital process that allows passengers to confirm their presence on a flight via an airline’s website or mobile app, usually beginning 24 to 48 hours before the scheduled departure. The process typically requires you to enter your booking reference (PNR) and last name. Once logged in, you can verify your flight details, select or change your seat, and declare any checked baggage. If the flight is international, the system may prompt you to input passport and visa information. After completing these steps, the airline issues a digital boarding pass, which can be saved to a smartphone "wallet" or printed at home. The primary advantage of online check-in is the time saved at the airport; if you only have a carry-on bag, you can bypass the check-in counters entirely and head straight to security. If you do have bags to check, many airports now offer "bag drop" shortcuts for those who have already checked in online. Additionally, checking in as soon as the window opens gives you the best chance of securing a preferred seat before they are assigned to other passengers or held for airport standby.