Keypads like the one seen to the left can be used in various ways. Normally they are used in traffic control applications.
A keypad can be “self-contained” and not require any external programming tool. You simply hit a key sequence to program your combinations.
Some keypads will store information like which combination was used at what time.
The limitation to simple keypads is that numeric combinations are easy to give to others who are not authorized to access the space. Also, someone can be looking over your shoulder and learn the combination.
So a numeric keypad is not used by itself for high level security. But it is very economical, can be used with your garage door opener or electric locks for traffic control. Other applications include locking and unlocking doors or machinery.