0_Apprentice
Is Equestrianism related to riding on a horse back?
1_Wizard
That is exactly what it is! Equestrianism is know as riding, horse riding, or horseback riding. This can even include vaulting with horses. 
0_Apprentice
What do you mean by the term vaulting ?
1_Wizard
vaulting is gymnastics and dance on horseback. This can be done in competitions. Also in competitions is rodeo, horse racing and even polo.
0_Apprentice
 Is it an olympic event?
1_Wizard
Yes Equestrianism made its Summer Olympics debut at the 1900 Summer Olympics in Paris, France.
0_Apprentice
Is it similar to hockey or polo sport?
1_Wizard
Maybe not hockey but yes to polo. Polo is played on horseback.