system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How do master keys work?

How does one key e.g. A hotel key (metal keys) have a pattern that allows them to open any door in that building? I thought keys had certain patterns and obviously keys don't shapeshift to fit each different lock pattern.

EDIT: grammar and update to say thanks for people's time to find YouTube videos etc.
Also, I'm not a burglar... No seriously I'm not. Okay now it just sounds like I'm trying to bluff. I shall leave.
gpt
A regular lock has a set of tumblers in it, each one has a groove cut in a certain spot so that when the key is put in, the grooves line up and the lock can turn. A lock with a master key has a second set of grooves cut in it so the unique key or the master key can open it.