Yes, you must check in whether you have luggage or not, but the way you do it depends on your preference. In 2026, most airlines require you to complete the "Online Check-In" process via their app 24 hours before the flight to secure your seat and receive your boarding pass. If you have luggage to "check" (place in the cargo hold), you still do the online part first, then go to the airport’s "Bag Drop" or "Self-Service Kiosk" to print your luggage tags and hand the bags to the airline staff. You cannot simply walk to security with a large suitcase. If you only have carry-on luggage, you can skip the airport desks entirely and go straight to security with your mobile boarding pass. Arriving at the airport without having checked in online can lead to long queues at the full-service counters and, with some low-cost carriers like Frontier or Ryanair, can result in an "airport check-in fee" of up to $25–$100.