1) The word "piano" contains three vowels: I, A, and O.

2) The Mongol Empire, under the leadership of Genghis Khan, became the largest contiguous empire in history, spanning from Asia to Europe.

3) The #MeToo movement, originating in 2006 and gaining widespread attention in 2017, raised awareness about sexual harassment and assault, encouraging survivors to share their experiences and promoting discussions on consent and gender equality.

4) The world's first stock exchange was established in Amsterdam in 1602.