How does Zalgo text work?

Question

I've seen weirdly formatted text called Zalgo like below written on various forums. It's kind of annoying to look at, but it really bothers me because it undermines my notion of what a character is supposed to be. My understanding is that a character is supposed to move horizontally across a line and stay within a certain "container". Obviously the Zalgo text is moving vertically and doesn't seem to be restricted to any space.

Is this a bug/flaw/exploit/hack in Unicode? Are these individual characters with weird properties? "What" is happening here?

H̡̫̤̤̣͉̤ͭ̓̓̇͗̎̀ơ̯̗̱̘̮͒̄̀̈ͤ̀͡w͓̲͙͖̥͉̹͋ͬ̊ͦ̂̀̚ ͎͉͖̌ͯͅͅd̳̘̿̃̔̏ͣ͂̉̕ŏ̖̙͋ͤ̊͗̓͟͜e͈͕̯̮̙̣͓͌ͭ̍̐̃͒s͙͔̺͇̗̱̿̊̇͞ ̸̤͓̞̱̫ͩͩ͑̋̀ͮͥͦ̊Z̆̊͊҉҉̠̱̦̩͕ą̟̹͈̺̹̋̅ͯĺ̡̘̹̻̩̩͋͘g̪͚͗ͬ͒o̢̖͇̬͍͇͓̔͋͊̓ ̢͈͙͂ͣ̏̿͐͂ͯ͠t̛͓̖̻̲ͤ̈ͣ͝e͋̄ͬ̽͜҉͚̭͇ͅx͎̬̠͇̌ͤ̓̂̓͐͐́͋͡ț̗̹̝̄̌̀ͧͩ̕͢ ̮̗̩̳̱̾w͎̭̤͍͇̰̄͗ͭ̃͗ͮ̐o̢̯̻̰̼͕̾ͣͬ̽̔̍͟ͅr̢̪͙͍̠̀ͅǩ̵̶̗̮̮ͪ́?̙͉̥̬͙̟̮͕ͤ̌͗ͩ̕͡

Egression

en.wikipedia.org/wiki/Combining_character might offer some clues. – Crustaceous

This might also blow your mind: en.wikipedia.org/wiki/… – Snaky

As the obligatory reference, xkcd.com/1857 – Bats

Answer 1

The text uses combining characters, also known as combining marks. See section 2.11 of Combining Characters in the Unicode Standard (PDF).

In Unicode, character rendering does not use a simple character cell model where each glyph fits into a box with given height. Combining marks may be rendered above, below, or inside a base character

So you can easily construct a character sequence, consisting of a base character and “combining above” marks, of any length, to reach any desired visual height, assuming that the rendering software conforms to the Unicode rendering model. Such a sequence has no meaning of course, and even a monkey could produce it (e.g., given a keyboard with suitable driver).

And you can mix “combining above” and “combining below” marks.

The sample text in the question starts with:

• LATIN CAPITAL LETTER H - H
• COMBINING LATIN SMALL LETTER T - ͭ
• COMBINING GREEK KORONIS - ̓
• COMBINING COMMA ABOVE - ̓
• COMBINING DOT ABOVE - ̇

Newby

Unicode can do this because it deliberatedly conforms to nothing but the "real world usage of characters" - software is then expected to conform to Unicode. And this is why we have e.g., U+1F4A9. – Denationalize

Just to add to this, here's a list of combining characters used above below, or through the text to generate "Zalgo text": zalgotextgenerator.com/unicode – Norven

@CamiloMartin I don't think I understand what you mean by "real world usage". Is there a language, for example, in which an H decorated with a small T, koronis, comma above and dot above, represents a meaningful textual concept, beyond "this is an H but there's a bunch of arbitrarily chosen stuff obscuring it"? If any of those decorations were removed or altered, would the semantics actually change? – Bonanno

Answer 2

Zalgo text works because of combining characters. These are special characters that allow to modify character that comes before.

OR

y + ̆ = y̆ which actually is

y + ̆ = y̆

Since you can stack them one atop the other you can produce the following:

y̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆

which actually is:

y̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆

The same goes for putting stuff underneath:

y̰̰̰̰̰̰̰̰̰̰̰̰̰̰̰̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆

that in fact is:

y̰̰̰̰̰̰̰̰̰̰̰̰̰̰̰̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆̆

In Unicode, the main block of combining diacritics for European languages and the International Phonetic Alphabet is U+0300–U+036F.

More about it here

To produce a list of combining diacritical marks you can use the following script (since links keep on dying)

for(var i=768; i<879; i++){console.log(new DOMParser().parseFromString("&#"+i+";", "text/html").documentElement.textContent +"  "+"&#"+i+";");}

Also check em out

Mͣͭͣ̾ Vͣͥͭ͛ͤͮͥͨͥͧ̾

Harragan

how would you type that? – Ikey

@Ikey If you are asking about ALT codes then you cannot do that you would simply paste y̆̆ where it gets into 'pure' html and browser would do it's magic... – Harragan

@barbsan Hi, thanks for letting me know, I have replaced it with a script that generates them. – Harragan

I wonder why did you choose this particular example of Y with a tildae. It actually has some meaning in Russian, not sure if you are familiar with that. – Heliogravure

@Heliogravure I think he uses this example because it is the very same example the linked wikipedia page (en.wikipedia.org/wiki/Combining_character) is using. – Muscarine

@Muscarine They don't use underscore tilde (y̰ y̰ ) in wiki example. I am fluent in Russian but have no clue about it. What does it mean? – Harragan

@MatasVaitkevicius Oh, my bad. I thought he meant the first example (y̆) – Muscarine

@Heliogravure what does underscore tilde (y̰ y̰ ) mean? – Harragan

@MatasVaitkevicius it's hard to explain to someone who is not native Russian without violating SO's rule for profanity and obscenity. Basically, there is a (most) obscene word in Russian which is 3 characters. If they were all to be drawn one over another you'd come up with a glyph which would very much resemble the one posted. Any native Russian speaker will immediately recognize this writing as obfuscated obscene word (in funny way, not insulting one). I think, this particular glyph was invented by Russian designer some decades back. – Heliogravure

@MatasVaitkevicius note the tilde is over the Y character, not under it. It makes difference. – Heliogravure

@Heliogravure Best I could come up with is this y͓ͥ there is no Cyrillic И over nor under, I am pretty sure if you would post the correct one (for educational purposes, we are all adults and one might want to filter it on the web) no one will mind... I am fluent in Russian and can talk by only using profanities (like average Russian ;) ) – Harragan

@MatasVaitkevicius I will spell it in reverse with spaces and god help me :) The word I am referring to is Й У Х. Draw all those letter one over another and you'll see something very similar to the thing. – Heliogravure

It's just the nickname for Richard. – Knish

@MatasVaitkevicius So you spelled it in Ukrainian... In 2024 we alas know several cyrillic swearwords very well :( – Knish