Regulators / Regs - this is what you use to get air from your tank into your mouth. They regulate the high pressure air in your tank, reducing it to the same pressure as the water around you, so breathing is easy.
First stage (regulator) - This is the part of the regulator that is attached to the tank, reducing the air to a safe pressure for the hoses.
Second stage (regulator) - This is the part that enters your mouth, the second part reduces the air pressure to the correct pressure.
BCD control device / buoyancy / jacket - not some kind of protection from combat, but a device that you wear (like a jacket) that helps you stabilize your buoyancy in water. With many pockets for storing other pieces of equipment, you add air to it to increase buoyancy and remove air to reduce buoyancy in search of neutral buoyancy.
wings
An alternative to BCD, its shape means that the air pockets are both sides of your tank (as opposed to those around you in BCD). This gives a smoother face aspect that is brilliant for diving, but can be a problem for a less experienced surface diver.
buoyancy - Do you swim, dive or swim? An object that will float smoothly will float, and one that will be smooth will dive, and a neutral one will float in water, and this is what we, as divers, wish for.
Measuring instruments - How much air do you have left? Your sensors will tell you about it. A simple glance will tell you how many air strips you have left. You start with 200 (maybe even 300) bars, and each breath slowly reduces the contents of your air cylinder until it becomes empty.
tank - Contrary to many television programs, the tank that we carry on our back does not contain anything other than normal atmospheric air, which has been discharged. This is not an oxygen tank - if you breathe pure oxygen deeper than about 6 meters, you will kill yourself. If you are not trained to use nitrox or other compounds, you simply carry normal air.
Open water - here you can familiarize yourself with open water certification, open water, open water dives, etc. All this applies only to reservoirs other than pools. From quarries to the oceans - all this is open water. Open Water Certification is a basic PADI certification that allows you to live without an instructor.
PADI / BSAC - These are the two main diving organizations, but there are still a lot of them. They provide reference material, establish training programs for courses, and control dive centers.
