Once upon a time, fans at rock concerts came in, sat down and listened. Maybe they stood on their chairs.

No more. With the advent of punk music came pogoing (jumping up and down) and, later, slam-dancing (as you might expect, slamming into each other).

The sweaty son of those two is moshing, the violent, roiling, seething mass-dance done by concertgoers at alternative, metal and industrial concerts, to the music of bands such as Green Day, Pantera, Ministry, Nine Inch Nails and Metallica. The mosh pit is the area, usually directly in front of the stage, where the action takes place.

Two of the more extreme forms of moshing are bodysurfing - essentially being borne aloft by other moshers, “surfing” above the crowd on the hands of those below - and stage-diving - flying or jumping, voluntarily or not, out of the pit to jump onstage for a brief moment of glory.

Moshing came to symbolize the anger and anti-socialism expressed in much of the music.

“These kids can’t smoke, they can’t drink, they can’t have sex - this is their release,” says Wayne Howell, a major American concert insurer. “Their parents had Led Zeppelin, and they have this.”

Jumping in the mosh pit became a rite of passage. Scenes of pit action began showing up on MTV. Performers starting diving into the pit in a show of solidarity.

By 1994, at the Woodstock II festival, fans were moshing to everything from Nine Inch Nails to Crosby, Stills & Nash. Dave Ferman