A life jacket is a device that is designed to help a person float and keep his or her head above water in swimming pools, rivers or the sea. Life jackets are commonly found at swimming pools, airplanes, boats, yachts and large ships and are placed in locations that are easily accessible to passengers and crew members.

It is equally important to wear a life jacket while participating in adventure water sports such as white water rafting. The life jackets are buoyant in nature, which means, they float in water without any action from the wearer.

Life jackets are usually made of tough synthetic fiber covering a source that provides buoyancy such as a chamber or air or foam. These jackets are available in bright colors such as yellow or orange, which help rescue personnel easily spot them in case of emergencies.

The earliest instances of use of life jackets can be traced to Norwegian seamen who used simple blocks of cork or wood to help a person float in case he fell overboard. The modern life jacket is said to have been invented in 1954 in the U.K., by Captain Ward, a Royal National Lifeboat Institution inspector. He fashioned a vest that used cork as a buoyancy device.

The various types of life jackets available include foam core, deep water, air chamber, underwater and specialized life jackets. Foam core lifejackets are usually the simplest and the least buoyant. Air chamber life jackets are used mainly on large transport vehicles such as aircrafts and cruise liners. These life jackets are usually created of vinyl and encapsulate air chambers that can be inflated. They provide more buoyancy than foam life jackets. Deep water life jackets are designed for long term immersion in water. They are also known as wet suits or dry suits.

Underwater life jackets are used by deep sea divers to adjust their buoyancy while they are underwater. Specialized life jackets are used for adventure water sports like river rafting or kayak racing and are highly buoyant.