What are devices called that are used to lock and unlock doors?

The term for devices used to lock and unlock doors is commonly referred to as "keys." Keys serve as a physical mechanism that interacts with the lock mechanism of a door, either by inserting them into a lock cylinder or by using them in conjunction with other devices like electronic locks. They are designed to fit specific locks, making them essential for controlling access and providing security.

While latches and bolts are components of locking mechanisms that keep doors secure, they do not function independently to unlock or lock a door without the aid of keys or other actuation methods. Keypads represent another method of unlocking doors, often utilizing numeric codes or other electronic inputs, but they still require the same concept of access control as keys, rather than providing a traditional locking mechanism themselves. Keys, therefore, encompass a broad and traditional method of securing doors and are integral to the locking process.