To my understanding, hardcore dancing originated with Circle pits where you basically ran left in a circle and flailed your arms into the onlookers. then towards the 90's modern hardcore dancing emerged. unlike the Souther californian circle pits, modern day moshing started in places like New York and Boston which had thriving hardcore scenes. with the rapid growth of the dance came the breakdowns. Bands soon had to incorporate sections where fans could dance a specific way. The breakdown usually has the guitarist/s playing a few repetitive chords on the lowest strings while the drummer hits the bass pedal each time the guitarist strums resulting in an almost militaristic, uniform sound which many fans can show off their newly learned moves.
The most common dance moves are:
2 step which basically crosses one foot in front of the other while staying in generally the same place and arms swing across.
the windmill is when you flail your arms forward to the beat of the song
picking up change: pretty self explanatory
spin kick, also self explanatory
the dancing can even be applied to deathmetal/hardcore hybrid bands. using hxc dance moves during fights is highly discourages as this is only a fashion.
Hardcore Dance is gay