Your carry-on luggage is the one, which you carry into the cabin of an aircraft.
Currently, there are no uniformly enforced airline restrictions concerning carry-on luggage.
Most carriers state that the bag must fit in the overhead bin or under the seat in front of you. The usual maximum measurements are said to be 55cm x 35 cm x 22 cm (non-metric: 22 X 14 X 9 inches), but many folks continue to exceed that and are allowed to do so. At most airports, there are bag checking " frames " that you can insert your carry-on into to see if it meets these " quasi-requirements." Enforcement seems to be uneven at best, and often totally lacking. If in doubt, be prepared to be asked to check your carry-ons
Other definition:
Carry-On is the luggage that is permitted to be carried on the plane by a passenger. Also known as ‘everything you own jammed into a bag" or ‘the luggage they can"t lose."
Other definition:
Carry-on is the unchecked baggage.
Other definition:
Carry-on is the luggage that is permitted to be brought on to the aircraft by the
passenger.
Other definition:
Carry on is the piece of luggage that a Traveler takes inside the airplane cabin and whose size does not (is not supposed to) exceed the allowed dimensions set by the airline.
Usually the Carry on luggage is stowed in the overhead bin or under the seat in front of the passenger.