Size
Carry-on bags must be small enough to store in an overhead bin or underneath the passenger's seat. The exact size can vary depending on the airline, but it is often around 10 by 16 by 20 inches.
Liquid Rules
Liquids are limited to 3.4-oz. bottles or smaller, and no more than three bottles per passenger. These bottles must be stored in a single quart-size plastic bag. The individual airline determines whether food can be brought on board.
Checkpoints
When passing through the security checkpoints, the aforementioned bags containing liquids must be removed from bags and scanned through the X-ray machines separately. This also applies for computers and other electronics.
Storage
Carry-on bags need to be securely stored in one of the two previously mentioned locations during takeoff and landing. They may be taken out after the "Fasten Seat Belt" sign has been turned off, both during the flight and after landing.
Electronics
Communication devices such as mobile phones must be turned off during the flight so they don't interfere with the pilots' communication equipment. Other electronic devices can be used following takeoff with permission from the captain.
