Ah, the good old days of airline travel! Decades ago, travelers could walk right up to the gate, snack on free meals, smoke in their seats – OK, some things have improved since then, but luggage rules have definitely gotten tougher. In the recent past, it was standard for airlines to allow coach or economy passengers to bring a piece of luggage and a personal item into the cabin for a flight. That's gradually changing as airlines fight with low-cost competitors for customers, while still making profits. Companies like American Airlines offer no-frills tickets at slashed prices, but make up for it by charging those customers for carry-on bags that used to be free.

How Many Carry-ons Can I Bring for Free?

It depends entirely on your airline and on the type of fare you've booked. Some major airlines operating in the United States still allow coach or economy travelers to bring a piece of carry-on luggage and a personal item onboard. But if you book a ticket in an airline's lowest tier, the rules may be different. For example, buying a Basic Economy ticket on an American Airlines or United flight limits the traveler to one personal item that can fit under a seat. Basic Economy passengers who arrive at the gate with a suitcase must pay not only the bag-check fee but a $25 handling fee too.

International airlines have their own baggage guidelines that may differ from those of your favorite domestic airline, especially for travelers who book fares in top tiers like first class. The rules also change depending on where a flight departs from and lands. Emirates' carry-on guidelines are different for passengers flying out of India than for those leaving Brazil, for example. Look for a baggage calculator on an airline's website to determine exactly what you're allowed for your specific itinerary.

While many airlines have gotten stricter about carry-ons, it's not all bad news if you're traveling within the United States. Major airlines, including JetBlue, Delta and Southwest, allow all passengers to bring a carry-on bag and a personal item. That's subject to change at any time, so check your airline's current restrictions before packing.

What Counts as a Personal Item?

In airline terms, a personal item is any bag that can fit completely under the seat in front of you. A purse, briefcase, laptop bag, backpack or small duffel bag generally all qualify as personal items. All airlines have slightly different guidelines for the maximum size for an acceptable personal item, but generally, they can't be larger than 18 by 14 by 8 inches. Keep in mind that the larger your personal item, the less space will be available for your feet.

Are There Any Carry-on Exceptions?

Yes. Diaper bags, coats, child safety seats and assistive devices, including breast pumps, strollers and walkers, won't be counted toward your carry-on allowance. Generally, airlines also allow passengers to carry on bags from the airport's duty-free shops in "reasonable quantities." It's up to the airline to determine whether or not the size of a passenger's duty-free purchase is reasonable.