Stand tall and prepare to plié. Yes, on Thursday, October 29, it’s World Ballet Day. Launched in 2014, the day is now in its seventh year. This year the Royal Ballet, the Australian Ballet, and the Bolshoi Ballet are streaming live rehearsals (following safety protocols, naturally), morning classes, and exclusive interviews. Lest you think ballet is too esoteric to deserve its own day, think again. Last year’s World Ballet Day attracted 315 million social media users around the world. —L.J.