This is the real reason why flight attendants greet you with their hands behind their backs

Who knew?

Whenever you board a plane, you're probably aware that a flight attendant welcomes you – it's pretty standard protocol for them to greet you when you board the plane.

You may have presumed it's nothing more than a matter of looking presentable, but there's more than meets the eye when they stand with their hands behind their backs while greeting you.

Their travel beauty secrets aren't the only thing they're hiding from us, because they're actually counting how many people are boarding the plane. They do so with a special clicker hidden out of sight, Bright Side reports.

So, when they head down the aisle and count everyone in their seats, it's actually the second time they're counting the number of passengers who are on the plane. More of a 'double check', if you like.

Maybe next time you're flying you can try to spot it as you walk past?

You really do learn something new every day...