Scuba equipment is mainly comprised of a buoyancy compensator (BC), a weighting system, a regulator and an oxygen tank. The BC and weighting system help a diver achieve neutral buoyancy, while the regulator delivers oxygen from the tank to the diver. A mask, snorkel and fins are also vital to a diving experience.
Depending on where you are diving, you might want to use a wetsuit to keep your body temperature consistent in colder water. Gloves and hoods are helpful for heat retention as well. Other useful items are underwater cameras, dive watches and dive computers.
All but the most advanced scuba divers own their own mask, snorkel and fins, and rent a buoyancy compensator, weighting system and regulator. All dive shops provide oxygen tanks with a trip or for rent.
To learn to properly use scuba equipment, you have to complete a diver certification course. Most dive shops offer a certification program that is authorized by SSI or PADI, which set the international standard for scuba education.
Scuba is a highly specialized sport that requires a substantial amount of training. Do not attempt it without completing a dive certification program through a reputable scuba school.