It's more so that it's matching the last instance of the thing you are looking for. Because, for instance, it won't match x if there is another x later on in the string, regardless of the characters in between. That's what (?!.*\1) is doing here - it's making sure that a match is not made when there is another x later on. In the context of this kata, then you can see it's actually helping us find only the last instance of each unique alphabet character.

does this regex mean that it matches any character? And when it finds a match it ignores all other matches in the string?

I tried running it in RegExr, and I got confused why it ignored "The" at the beginning of the string but matched 'the' elsewhere.

simmilar site - https://regex101.com/

It hides your message for those who didn't solve the kata.

Please use spoiler flag next time, or anyone is able to see your message from the dashboard.

This is called or like state machine?

it's a minimalist solution :)))

Can anyone tell me what (is ?!.*\1) mean?

Holly molly!