For two weeks every four years, women’s gymnastics is one of the biggest sports in the world. The rest of the time, those of us watching are kind of a niche group.

That can make it hard to fully appreciate what you’re seeing when the athletes take the Olympic stage. If you want to know what’s required on each apparatus or how to distinguish good routines from great ones, we’re here to help.

Here, we’ll look at the balance beam, starting with a broad overview and then moving into the technical details. We also have guides to the vault, uneven bars and floor exercise.

The beam is about 16 feet long, about four feet high and about four inches wide — not much wider than a credit card.

Every routine must include:

A successive series of two or more acrobatic skills (handsprings or flips). At least one must be a salto, meaning no hands.

Two or more consecutive dance skills (turns, leaps or jumps). At least one must be a leap or jump featuring a 180-degree split.

Acrobatic skills in multiple directions (backward versus forward or sideways).

At least one turn or pirouette.

Gymnasts receive one score for difficulty and one for execution, and the two are combined for their final score. In the best beam routines, the gymnast has no wobbles and, of course, no falls. (In reality, small balance checks are common.) Judges also deduct for poor form and excessive pauses between skills.

The reigning Olympic champion is Guan Chenchen of China, and the reigning world champion is Simone Biles of the United States.

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