The " Bit Key " is commonly referred to as a skeleton key. Make no bones about it, these keys were all that stood between you and the village pillagers. The bit key fits into what is known as a Warded Lock. These locks feature a keyhole with a cylinder on the far end. Inside the keyhole were a series of concentric plates, or wards, that would block a key from turning unless the pattern of notches on the key matched the pattern of wards. If the key turned freely, it would engage or disengage the bolt when turned.
Warded locks remain in use today, though they’re largely found at historic sites where they’ve been keeping out imposters for centuries. The keys themselves will look familiar to anyone who’s ever dreamed of living in a castle or joining a secret society. They’re beautiful!