Passengers are not allowed to have box cutters, blades, firearms, ammunition, explosives, flammable liquids and gels, or hazardous chemicals in any bags they'll have access to in the passenger compartment. Some items such as martial arts weapons, tools, unloaded guns and sports equipment such as bows and arrows, golf clubs and spears can be checked but must be declared and secured in cases that will not cause injury to baggage handlers.
Liquids in carry-on bags and purses must not exceed three fluid ounces and all combined liquids must fit in a single one quart clear plastic zip-top bag. Each passenger is limited to one plastic bag. Additional liquids, however, can be placed in checked baggage.
Although the rules vary amongst domestic and international carriers, the general rule is that each passenger is entitled to bring one carry-on that fits under the seat or in the overhead bin and one personal item such as a purse, briefcase, or laptop computer. Checked luggage cannot exceed dimensions of 45-by-55-by-62 inches, and passengers are charged extra if they have more than one checked piece.
In addition to size limits for carry-ons and checked luggage, there are strict rules about their weight. Carry-on items can't weigh over 40 pounds. Checked bags can't exceed 70 pounds. If the bags are overweight, passengers are changed an extra fee for them which can be as high as $200.
All bags must carry visible ID tags and checked items must have TSA-approved locks.
With the exception of service animals such as seeing eye dogs, only small pets in carriers that can fit under the seat are allowed in the main cabin. Larger animals need to be in approved transport crates and placed in the hold. A passenger is only allowed one pet in the cabin, and airlines have restrictions on how many animals are allowed in the cabin on a single flight.
