The modern monarchy are progressive in so many ways.
From Prince Harry and Meghan Markle's groundbreaking wedding, to Princess Charlotte being the first female royal in history not being bumped down the pecking order with the arrival of her male brother Prince Louis.
But despite this, there's just some traditions that are here to stay. Perhaps the most intriguing royal rule is the art and the politics of the curtsy.
While us mere mortals are content with greeting our family with a hug, if you're a British or European female royal you'll be getting your bob on to anyone above you in the social rank.
The gesture is the ultimate mark of respect and the "court curtsey", a deep and elaborate pose, is the preferred method.
"The royal curtsy is one foot behind the other and the deep and the longer you stay down shows more respect," Australian School of Etiquette, Zarife Hardy tells Now To Love.
Interestingly, after Duchess Catherine married Prince William in 2011 The Queen reportedly updated the Order of Precedence document and Kate must curtsy to "blood princesses" including Princess Royal, Princess Alexandra, and the daughters of the Duke of York, Princesses Beatrice and Eugenie, who are below her in pecking order.
This rule does not apply if she is joined by Prince William.
From Princess Diana, Meghan Markle and Duchess Catherine, keep reading to check out the best royal curtsies of all time!