Permissible items in carry-on and hand luggage include electronic devices (such as laptops, tablets, and smartphones), clothing, books, and necessary medical equipment. Liquids, gels, and aerosols are strictly permitted only in containers of 100 milliliters or smaller, all fitting inside a single transparent, resealable plastic bag. Prohibited items that must never enter the cabin include sharp objects, firearms, explosives, flammable chemicals, and tools that could pose security risks, all of which are heavily regulated by aviation security agencies.