ELI5 Locks and Keys - aren't there high chances that two keys are the same?

Did you know a standard lock might have thousands of combination possibilities, yet yours might open someone else's door? How does a master key work such that it can open multiple locks without compromising security entirely? What makes lockpicking more of an art than a science, requiring skill and a deep understanding of how locks function? How can a particular ""jiggle-and-twist"" method sometimes allow a key to open unintended locks successfully? What surprising connections do locks and keys have with human ingenuity and security throughout history?

... we explain like I'm five

Thank you to the r/explainlikeimfive community and in particular the following users whose questions and comments formed the basis of this discussion: QvttrO, TehWildMan_, DJpng, thephantom1492, Childofglass, Jack_Chronicle, Git_Off_Me_Lawn, woofle07.

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