"One-key-fits-all" locking systems
For the small household, indispensable; for buildings with more than three locks (to be more exact, three door cylinders) a matter of some importance - a locking system.
ABUS uses part of the principle of locking systems for many and varied types of lock. What is meant is that, apart from your bicycle lock, you can also operate the front door lock and the padlock on the garden shed all with just one key (the technical term here is "single-key system"). But this is just one aspect of a locking system.
Perhaps it is best to explain how it works using a fictitious example:
Let's take a normal apartment building. The building has 8 rented apartments. There are also rooms to which only the landlord may have access, other rooms which are only for the tenants and the main entrance doors should be able to be opened by all the residents. This is where the master key system comes into play. Imagine that each key represents an access code (in the case of a key, this is managed using the key's profile, in other words, the ridges or drilled recesses on each individual key). The landlord's key is so designed that every cylinder in the house can be opened with this key (master key), the tenants' keys so that they can open the doors they need but they cannot open the landlord's doors. And the janitor with his key only has access to selected rooms. In short, the master key system defines who has access to which rooms. Thus, none of the residents needs to carry around several keys - with just one key they can lock and unlock the doors to which they are entitled.