As the description says, lock impressioning has been a long time staple of professional locksmiths around the world for years, and has become a popular past time in locksport clubs and events.
Lock impressioning is the act of taking a key blank, inserting into a lock, wiggling it around in order to have the key pins leave some marks on the blank, then filing those marks, and eventually making a working key from that blank, without having to take the lock apart. A great skill to have and yet another facet to the exciting hobby of locksport!
Hope you all enjoy new section dedicated specifically to impressioning.
Squelchtone