Rules about what you may or may not carry with you on an airplane are not hard and fast.

The main guideline to keep in mind is the "3-1-1 Rule." This means you may usually carry aboard liquids in three-ounce containers or less, in one quart-, zip-closing and transparent plastic bag, in one carry-on bag per traveler.

Here are some tips to ensure a smooth airplane boarding process:

• Usually, you'll be allowed one carry-on bag of a certain maximum and weight (usually 45 linear inches and 40 lbs.), plus a personal bag. Apparel, food for immediate consumption, baby supplies, umbrellas, walking aids, and reading matter are also allowed.
• Your personal bag should include your medications (at least enough to get you through a day or two if you're separated from your luggage), and perhaps toiletries and other necessities.
• Items that should go in checked baggage include foods, perfumes, and alcoholic beverages. You may carry fragile foods such as cakes and pies into the cabin, but they may be given extra attention from screeners. Gifts may also be unwrapped by security personnel.
• Avoid carrying cameras and film aboard; put this in checked luggage if you can.
• Pack your carry-on baggage in an organized fashion, so it is easy to search. Pack fragile items (such as computers) between layers of soft items (such as clothing).
• If you're unsure whether a certain item is allowed in a carry-on, put it in checked luggage or leave it at home.
• Always carry photo ID on your person: preferably your passport.