What are these characters and why are they rendered this way?

Question

I want to understand what is happening when these characters are displayed that they are displayed the way they are displayed.

I saw it on social media (FB and Twitter) and can't seem to understand what's technically happening.

Edit: If they characters from a character set I don't have installed I still don't get why they tend to not be displayed in a line and overlap other space even outside their line?

!̸̶͚͖͖̩̻̩̗͍̮̙̈͊͛̈͒̍̐ͣͩ̋ͨ̓̊̌̈̊́̚͝͠ͅ ̷̧̢̛͖̤̟̺̫̗͚̗͖ͪ̏̔̔̒́ͥ̓ͫ̀ͤ̇ͥ͝ ̡̊͛̇ ͫ̉ͦ̊̀̔ͧͮ͆̽ͦͩ͋̌͗̚̚҉̵͖̟͙̮͈̼̹̞͝ͅ

Answer 1

It's the magic of Unicode.

Unicode handles all extant writing systems of the world, and that includes the ones with symbols instead of letters, the ones that are written right-to-left instead of left-to-right, and the ones which are written top-to-bottom. It also contains provisions for how to render glyphs that are technically combinations of base and modifier glyphs (even 16 bit isn't enough for all possible accented, composited, or context-adapted characters in all languages). (Trivia: The Unicode standard is so complex and contains so much code that security issues have actually been found in it.)

Any software that claims to support Unicode fully has to be able to follow all these rules, and that includes stacking characters on top of each other, overlaying them etc. etc. This means that any person with an internet connection who connects can have their native language rendered correctly - but I dare say that on English-language boards the predominant use of all those features is to render cool pseudo-graphics, as in your example.