Skydiving is the sport of exiting an aircraft in flight, falling freely for a period, then descending under a parachute to land. In the United States it is practised at drop zones — airfields with an operator, aircraft and instructors set up for it.
What a jump actually looks like
An aircraft climbs to altitude, typically somewhere between 10,000 and 14,000 feet depending on the aircraft and the drop zone. Jumpers exit, fall freely for roughly 30 to 60 seconds, then deploy a parachute a few thousand feet above the ground and fly it back to a landing area.
The freefall portion is shorter than most people expect and the canopy flight is longer — commonly five to seven minutes. Much of the skill in the sport is in flying the parachute, not in the fall.
The three ways people start
A tandem jump attaches you to an instructor on a single harness system. It needs a short briefing rather than a course, which is why it is how most people experience skydiving once.
Accelerated Freefall (AFF) is the most common route to jumping alone: you exit with instructors alongside you from the first jump, deploying your own parachute.
Static line and IAD progression start from lower altitude with the parachute deployed at or immediately after exit, building toward freefall over a series of jumps.
How it is regulated
In the U.S., skydiving operations work within FAA regulations covering aircraft, pilots and jump operations. The United States Parachute Association is the sport's governing body and sets Basic Safety Requirements that its Group Member drop zones agree to follow, along with issuing licences and instructor ratings.
USPA membership is not a legal requirement, but Group Member status is a useful signal that a drop zone has committed to those standards.
These pages explain what things are so the language makes sense. They are not instruction and cannot substitute for it — skydiving is taught in person by rated instructors at a drop zone, and anything involving equipment handling or emergency procedures belongs there rather than on a web page.