For a short-haul flight where you are only taking hand luggage, checking in online saves a lot of time and is therefore much better than checking in at the airport. If, on the other hand, you have to check in bulky luggage, it is better to use the classic check-in at the airport for security reasons.

Checking in online makes a substantial difference in the efficiency and predictability of your travel day. Beyond simply skipping the longest queues at the airport, online check-in (usually available 24 hours before departure) allows you to secure your preferred seat before the majority of passengers arrive at the gate. This is especially critical for those traveling in groups or families who want to ensure they sit together. For the airline, your online check-in confirms your intent to fly, which can sometimes protect you from being the first person "bumped" in an overbooking situation. If you are not checking luggage, you can bypass the "Landside" counters entirely and head straight to security with a mobile boarding pass. Furthermore, many airlines offer the opportunity to prepay for baggage at a discounted rate or purchase cabin upgrades during the online check-in flow that might not be available at the airport. It also provides an early warning if there are documentation issues, such as a missing visa or an expired passport, giving you a few extra hours to address the problem at home.