Skydiving is a sport where participants jump out of airplanes with parachutes. Once the diver has fallen to a certain altitude, the parachute is activated, and the diver lands safely on the ground.

Skydiving is an activity where participants, at a pre-planned height, jump out of a plane and parachute to the ground. It is performed as a recreational activity and a competitive sport, as well as for the deployment of military personnel Airborne forces and occasionally forest firefighters. Skydivers can participate both in competitive and in purely recreational skydiving events. World championships are held regularly in locations offering flat terrain and clear skies. An exception is Paraski, where winter weather and ski-hill terrain are required. There are several different disciplines to embrace within parachuting. Each of these is enjoyed by both the recreational (weekend) and the competitive participants. There is even a small group of professionals who earn their living with parachuting. They win competitions having cash prizes or are employed or sponsored by skydiving related manufacturers.

The goal of skydiving is to dive out of a plane at high altitude and parachute down to the ground safely.

In many countries, either the local regulations or the liability-conscious prudence of the dropzone owners require that parachutists must have attained the age of majority before engaging in the sport.

The history of parachuting is not clear. It's known that Andre-Jacques Garnerin made successful parachute jumps from a hot-air balloon in 1797. The military developed parachuting technology first as a way to save aircrews from emergencies aboard balloons and aircraft in flight, later as a way of delivering soldiers to the battlefield. Early competitions date back to the 1930s, and it became an international sport in 1951.

Altimeter
Automatic Activation Device
Data Card
Goggles
GPS
Jumpsuit
Parachute (Rig)

Despite the perception of danger, fatalities are rare. However, each year a number of people are hurt or killed skydiving worldwide. About 30 skydivers are killed each year in the US; roughly one death for every 100,000 jumps.

In the US and in most of the western world skydivers are required to carry a second reserve parachute which has been inspected and packed by a certificated parachute rigger (in the US, an FAA certificated parachute rigger). Many skydivers use an automatic activation device (AAD) that opens the reserve parachute at a safe altitude in the event of failing to activate the main canopy themselves. Most skydivers wear a visual altimeter, but some go as far as using audible altimeters as well.

There are ways to practice different aspects of skydiving, without actually jumping. Vertical wind tunnels can be used to practice skills for free fall ("indoor skydiving" or "bodyflight"), while virtual reality parachute simulators can be used to practice parachute control. Beginning skydivers seeking training have a few different options available to them: tandem skydiving, static line, instructor assisted deployment, and accelerated freefall. Skydiving has complex skills that can take thousands of jumps to master, but the basics are often fully understood and useful during the first few jumps.

Accelerated Free Fall - training on freefall jumps of 40 seconds or longer, accompanied by a qualified jumpmaster, as opposed to Static Line training which does not involve long freefall in the initial training phase

Backslide - to move backwards in freefall relative to a neutral reference

Bag - the deployment bag in which the canopy is packed

Boogie - a group of skydivers usually focused on fun rather than competition

Brakes - brake lines on the canopy and are synonymous with steering lines; used together, they slow down the skydiver

Canopy - the construction of fabric and lines used to land safely after a freefall; the parachute

Cut Away - to release the main parachute; cutting away is a standard emergency procedure prior to deploying the reserve

Decision Altitude - the altitude at which a skydiver is trained to begin execution of emergency procedures

Drop Zone - common slang term for a skydiving center

Fall Rate - speed at which a skydiver falls

Flare - the act of pulling down the brakes of the canopy in order to slow it down, resulting in an increased angle of attack and reduced descent rate

Glide Ratio - distance a canopy flies forward compared to downward

Hand Deploy - to activate the parachute by manually deploying the pilot chute as opposed to pulling a ripcord

Main - the primary chute

Pilot Chute - a small, round parachute that acts as a drogue to extract the main parachute from the container and deploy it

Reserve - the auxiliary parachute carried on every intentional parachute jump

Rip Cord - the deployment system on all reserves and most student parachutes; the ripcord is a piece of cable with a handle at one end and a pin at the other that when pulled, releases the pilot chute

Rig - skydiver slang for the entire parachute, including main and reserve canopies and the harness/container

Tandem - parachute jumps in which two skydivers, usually an instructor and student, share one parachute system; the student is in a separate harness that attaches to the front of the instructor's

Terminal Velocity - speed at which drag matches the pull of gravity, resulting in a constant fall rate

Wuffo - skydiver slang for people who don't jump

http://en.wikipedia.org/wiki/Parachuting
http://www.longislandskydiving.com/skydiving-glossary.asp#dc