How does the text "Zalgo"?

This line is written using unicode combinable characters . And Unicode is such a system for coding in general all possible elements of any writing that exists now, existed once (dead languages) and even for some made-up (for example, Klingon language). In Unicode, there are more than one hundred thousand characters ¹ and each has its own number, which is written like this: U + <hexadecimal number>. For example, the Latin letter A ² is U + 0041 .

In writing of many languages ​​there are diacritical symbols - these are icons that are added to a letter and as a result either a new letter (e → ё) is obtained, or some additional meaning of the same letter (for example, stress).

There are a lot of such icons: the imagination of humanity has invented dozens of circles, hooks, dots, dashes and other things. It would be very difficult to fit into the standard a combination of each of these icons with each possible letter. Therefore, combinable characters were invented and developed.

It works like this. There is a Latin letter A We need to write this letter with a circle at the top to make Å . To do this, we use the base letter A , and after it we put the combined symbol ˚ - U + 030A "Combined riser circle" ³ . In fact, these characters go separately one by one, but the browser (or text editor) can combine them, so it shows them together .

Combinable characters can be added not only from above, but also from below: A͢, and even directly on top of the character: ̸A. You can even immediately everywhere: ̸Å͢.

What will happen if after one “basic” symbol to put a multiply combined? Get a column of characters, like this: Å̊̊̊̊̊̊̊̊. That is exactly what Zalgo-text is.

The text above is written as simple as possible and contains a number of factual inaccuracies. Below are notes for professionals.

1. In fact, not characters, but code points (code points), which are assigned (assigned) some abstract character (abstract character) or other role. The total possible code positions are 1114112 ₁₀ or 17 × 2 ¹⁶ (from 0 to U+10FFFF ) and for the most part nothing has been assigned yet.
2. In fact, A should be called an abstract character, which is assigned the code position U + 0041. An abstract symbol contains only the idea of ​​the letter A, but does not define any specific mapping (glyph). Specific images are contained in fonts.
3. This is not the only way to get an abstract symbol Å . Two Unicode code positions are assigned directly to this symbol: Latin capital letter A with a circle on top of U + 00C5 and Angstrom Sign U + 212B . This is far from an exception; many abstract symbols have assigned code points (1 or more) and are “assembled” using combinable symbols. All abstract characters that are assigned their own code points are called assigned characters .

A similar question in English: How does Zalgo text work?