system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: I am living in a building where we are several students with one room each and we share a kitchen. How is it possible that all our keys to our rooms fit the lock to the kitchen, but not the other student's rooms?

Everyone have a key that fit the lock to their own room and the lock to the kitchen, but not to the other student's rooms.
gpt
A lock has a number of tumblers, which all need to be pushed to a certain height in order for the lock to turn. Each key is unique, and the bumps on the key correspond to the heights of the tumblers within the corresponding lock.

Imagine keys and locks as a 6 digit password. Now imagine that your kitchen lock is only a 4 digit password - the kitchen lock only has 4 tumblers, not 6. So your keys can all open the kitchen door if they have the right 4 bumps, but you can't open each other's doors.

Imagine the kitchen door is 0134. Imagine your door is 013461 and your roommate's door is 013413. You and your roommate can both open the kitchen because your keys have 0134 (which is all the kitchen needs,) but you can't open each other's doors because your keys don't match the lock.