Wiktionary
n. the practice of jumping from the stage in a rock concert to be caught and carried aloft by the crowd
Wikipedia
Stage diving is the act of leaping from a concert stage onto the crowd below. It is often the precursor to crowd surfing.
Long before the word was invented, public stagediving took place during the first Dutch concert by The Rolling Stones at the Kurhaus of Scheveningen on August 8, 1964.
Many musicians have made stage diving a part of their stage act. Jim Morrison was an early performer known for having jumped into the crowd at several concerts. Iggy Pop is often credited with popularising stage diving in popular rock music. Initially seen as confrontational and extreme, stage diving has become common at hardcore punk and thrash metal performances.