Be careful what you copy: Invisibly inserting usernames into text with Zero-Width Characters
https://medium.com/@umpox/be-careful-what-you-copy-invisibly-inserting-usernames-into-text-with-zero-width-characters-18b4e6f17b66
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Zero-width characters are invisible, ‘non-printing’ characters that are not displayed by the majority of applications. For example, I’ve inserted 10 zero-width spaces into this sentence, can you tell? (Hint: paste the sentence into Diff Checker to see the locations of the characters!). These characters can be used to ‘fingerprint’ text for certain users.