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If you are wondering what is a sheet or web supported by springs in a metal frame and used as a springboard, the answer is: it’s a trampoline.

Explanation:

Trampoline on the grass.
Source: https://en.lifeder.com

A trampoline consists of three parts: a metal frame that keeps the form together, a flexible sheet or web, which is usually made of nylon, and springs that allow for an additional bounce.
Some trampolines also have fences for additional safety.

Many people enjoy trampolining because it’s fun for both adults and children. Trampolines can be placed both indoors and outdoors, although an outdoor trampoline would allow bouncing higher.

If you have kids, a trampoline in your backyard can keep them occupied for a long time. Some people choose to practice trampolining as a sport and perform various tricks while bouncing. Trampolines are also used in gymnastics and some other professional sports.