A personal flotation device (abbreviated as PFD; also referred to as, lifejacket, life preserver, Mae West, life vest, life saver, cork jacket, buoyancy aid, flotation suit, etc.) is a device designed to assist a wearer, either conscious or unconscious, to keep afloat.
Devices designed and approved by authorities for use by civilians (recreational boaters, sailors, canoeists, kayakers, etc.) differ from those designed for use by passengers and crew of aircraft (helicopters, airplanes) and of commercial vessels (tugs, passenger ferries, cargo ships). Devices used by military (army, air force, special forces, marines, navy, coast guard) and police and enforcement agencies generally have features not found on civilian or commercial models, for example compatibility with other worn kit (e.g. survival vest, bulletproof vest/body armor, equipment harness, rappelling harness, parachute) and use of ballistic nylon cloth to protect pressurized carbon dioxide (CO2) canisters used for inflating the vest from injuring the wearer if struck by a round from a firearm. The ballistic cloth keeps the fragments from the canister from becoming shrapnel injurious to the user.
PFDs are available in different sizes to accommodate variances in body weight. Designs will differ depending on convenience preferred for various levels of protection.
A lifejacket is a type of personal flotation device designed to keep a person's airway clear of the water whether the wearer is conscious or unconscious. They are either made from two layers of bonded polyurethane to be inflated or from foam.
The inflatable lifejacket is probably the most widely used for both leisure and commercial activities, while the foam lifejacket is predominantly designed either for children, or for emergency use (such as on ferries, cruise ships etc.).