Scuba, a common word, is actually an acronym for Self Contained Underwater Breathing Apparatus originated in 1939 to refer to US military diver's rebreather sets used by the Navy. A Scuba set is basically an independent breathing equipment, equipped with breathing gas that enables divers to stay underwater for considerably long periods of time. The Aqualung was the first modern scuba diving equipment invented by Jacques-Yves Cousteau and Emile Gagnan in 1943.

Scuba diving, which was initially intended for military and scientific use, has now become one the most popular recreational water sports around the world today. Children, as young as 10 years old, can now get Open Water Diver Certification (junior) from various centers. Scuba diving can be a lot of fun for people who love marine life, commonly used by recreational divers for fish identification, search and recovery, underwater photography or videography, etc. However, since scuba diving is a fairly dangerous sport, it is recommended by experts to take necessary lessons or certifications before pursuing the sport as a hobby.

Commercially, scuba diving is used for underwater constructions such as oil platforms, bridges, docks, dams, nuclear power plants and other coastal structures. Scuba diving, which involves scientific surveys and inspections, is known as scientific diving, which is exclusive to scientific purposes such as underwater experiments and underwater archaeology. As for the military, scuba diving has been put to use for naval ship repair and construction, and includes specialized diving divisions such as explosives ordnance disposal and combatant divers.

A person has to be at least at least 15 years old to get the open water diver certification, in good health and be able to swim 200 yards using any stroke, and float or tread on water for about 10 minutes. Some of the most popular and biggest scuba diving certification agencies include PADI, NAUI, YMCA, Scuba Schools International, and PDIC. These organizations offer some of the best scuba courses and training instructors available. There is also a Junior Open Water Diver Certification for people between ages 10 to 15, provided by agencies such as Bubblemakers, Scuba rangers, and SASY.

Basic scuba diving equipment includes accessories such as the mask, fins, snorkel, weight belt etc. There are two main types of scuba sets - open-circuit and closed-circuit.

Most scuba divers use standard air - 21% Oxygen, 79% Nitrogen - for their open-circuit scuba sets, which is much more cost-effective than using mixtures such as heliox and trimix. The open-circuit scuba set (also known as Aqualung) itself is quite simple so is also cheaper and more popular than other types. Basically, the user breathes in from the set and out to waste, with the gas cylinder worn on the back. There are 2- and 3 backpack cylinders open-circuit scuba sets available.

Closed-circuit scuba sets use rebreathers. In this system, exhaled air is reprocessed by the rebreather to make it fit for re-inhalation. This can be very economical for people who need to take long dives. The three types of rebreathers include oxygen, semi-closed circuit and fully-closed circuit rebreathers.