Unicode text exceeding boundaries?

Question

I've seen this before on youtube comments and such as well but what is this called and how is it done?

I saw it here https://stackoverflow.com/questions/1732348/regex-match-open-tags-except-xhtml-self-contained-tags/

Here's an example: h͚͔͕͍̣̙̞̃ͯt̖̗͎̩̳̻̆͑̈͐̉̐̚t͔͈̠̙̦̱͌̌͛́ͅͅp̱̞̓ͩͅ:̮̜̹̜͔̼͍ͪ̍̓ͨ͊̍ͥ/̖̮̘̰͕̯͈̱̺̓̎ͮ͐̈́/̿̍̓̑͌̔‌​̭̥̙͓̱̤͙͙ḳ̺̬̭̗͌̔ͩ͊̔̚ͅn̳͉̪̰̿ͦ̆̆o̥͎̮̠͌͋w͇̬̫̗͈̰̯̎ͤ̈́̈́ͮ͐́y͔̗͎̖̲̜͖̟̽͊ͪ͒̆̈ͪ̚ŏ̥͚̦̰͚͂̀̐ͧ̂‌​̞ù̠̩͖͓̦̆ͥ͂ͯr̜̣̝̘̬̖̲̓͛̓ͤ͛͗m͇̞̹̻̣̼͔̐̈e̖̻̲̺̩̟̙̮͑ͫ̋̇m͇̘̜̼̊ͤ̑̂e̲͉̦͉͉̓̉ͦ͂̋.̪̮ͯ͊ͪ̍̇͑͋͊̚‌​͓̺c͉͎͚͚̳̙̘̱ͤ͊͗͒͗̀ǒ̭͕̼́̈́ͅm̠͓̜͒̉/̹̳͎̯̥̪̮͗͛m̖͓̫͓͉͉̙̹̀̾͐ͧͪ̽ͥͥě̤̜͈̽̋̽ͮ̓̏̂m̻͆̊̅̎͂͆ͣ̍̾‌​͇̖̮͇̖̘̱͙e͙͍̻͕̤̾ͩ̄ͮ̈ͮͅs̘̺͕̳͂͑͒͆͐/͈͚̪̮ͨ͊ͨͯ̈́ͩ͌̚z̞͖̬͇̅ͨ̋̊ͬͩ̏ä̟͕͇͇̹̹ͤ̂̈́̂̌̒̆l̹͓̬̮̰͊̑̌̾‌​g̘̘̟͇ͣ̍̿̊̆͑̑ͅo̯̺͉͖̭ͥ̃ͣ̊̐̽ It can overlap text above and below it.

Answer 1

It uses combining diacritic marks. There are several ways to insert them.

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The ways to insert characters vary by platform, software, keyboard, etc., so an answer that covered just the dozen or so most common ways would have the length of a small book. If I ever wanted to do things like this, I would probably use my own keyboard layout where common combining diacritic marks can be entered directly on the keyboard.

Or maybe I would use MS Word mathematical mode, since I just learned that in it, you can enter e.g. a combining acute with \acute et