If you've ever taken a shot with a bartender, that bartender has probably chosen Fernet-Branca. Over the years, the liqueur has gained an almost cult-like following.

The bitterness and soothing properties of Fernet have made it so beloved. For bartenders, it's almost like a secret handshake — a sign of the end of a long night.

This liqueur is made from ingredients like rhubarb and myrrh, along with spices such as cardamom and saffron, and tastes strongly of black licorice, earthy bark, and roots.

Buying your bartender a shot of Fernet can indicate that you appreciated their service or that you're well-versed in drink culture.