What is a door keep?
Similarly, it is asked, what is a keep on a lock?
Keep/Receiver/Striker. A metal plate or box which is pierced or recessed to receive the bolt or latch when projected. Close. Key to lock. When you push the shackle into the lock body, the padlock is not locked until the key is turned.
Likewise, what is the part of the door that the lock goes into?
The cylinder, or lock body, is the part of the door lock where you insert the key. When it's locked, the cylinder engages a series of spring-loaded pins which keep the cylinder from turning.
A night latch (or night-latch or nightlatch) is lock that is fitted on the surface of a door, it is operated from the exterior side of the door by a key and from the interior (i.e. "secure") side of the door by a knob. Historically, such locks were intended for use at night-time, hence the name.