system
Given the following post, respond as if you're commenting on Reddit:
human
[Doctor Who] When the Doctor sonic screwdrives a doorknob, is he doing anything to it beyond just locking it?
gpt
When the Sonic Screwdriver was first introduced it did exactly what the name suggests; sonically rotate screws in or out of a screw hole. From there it isn't a massive leap onwards to say that in rotary locks it rotates the block and shifts the pins to lock or unlock it without the key.

These days however, the sonic screwdriver does a lot of things so while it locks the door, it probably scans the type of metal used, the stiffness and shape of the lock, reading for alien DNA on the surface and all other sorts of things where the Doctor's mind wanders while he uses it.