system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What is a chronon and what evidence is there that it actually exists?
gpt
> What is a chronon

It is a proposed unit of time that represents the smallest individual unit of time.  There is another proposed unit of time, called the Plank Time, which is another possible theoretically smallest individual unit of time.  (Much like the Plank Distance, which is possible theoretically smallest individual unit of distance.)

Both units of time are proposed the smallest quantum, they assume time is not continuous but has tiny steps between each instant.

It is also used in fiction as a particle or blob of time, mostly as a plot device for people moving through time in the story.

> what evidence is there that it actually exists?

For the unit of time version, that's like asking what evidence there is that a second exists, or that a minute exists.  It is an extremely short period of time, possibly the shortest discrete unit of time, much like the numbers 1, 2, 3, 4.  If the theories are correct then fractional time between them like 1.02 or 2.412 don't actually exist, they're bumped to the nearest time increment.

For the fictional particle, they're something writers like to use for plot twists, and they don't actually exist except in the book, movie, or game.