Here’s the thing that confuses almost everyone: the “fonts” you copy from a fancy text generator are not fonts. A font is a file (like Arial.ttf) that decides how a character is drawn — change the font and the same letter ‘A’ looks different, but underneath it’s still the code point U+0041. A real font can’t travel through a copy-paste, which is exactly why Instagram and Discord have no font picker.
What you’re actually pasting is different characters. Unicode — the standard that assigns a number to every character — contains thousands of letter-like symbols beyond the basic alphabet: a Mathematical Bold ‘𝐀’ (U+1D400), a Script ‘𝒜’ (U+1D49C), a Fullwidth ‘Ａ’ (U+FF21). They were added for math, typesetting and legacy compatibility — not for bios — but because they’re real code points, they survive copy-paste into any text field.
So a “bold text generator” is really a character-substitution map: it takes your ‘A’ and swaps in the Mathematical Bold ‘𝐀’. No styling is applied; the letters are simply replaced with look-alikes that already exist in Unicode. That single fact explains every behavior people find mysterious.
It explains why there’s no bold or italic for Cyrillic or most non-Latin scripts: Unicode only ever defined those mathematical alphabets for Latin (and Greek/digits). There is no ‘bold Д’ code point to swap in, so honest tools fall back to small-caps, spacing and decorative wraps for Russian instead of pretending. It also explains accessibility problems — screen readers see U+1D400, not ‘A’, and often read styled text as gibberish or skip it.
It explains the boxes and the breakage too. If a device’s fonts don’t include a glyph for that exotic code point, you get a ☐ tofu box. And styles built from combining marks (strikethrough, underline, zalgo) aren’t substituted characters at all — they’re accents stacked on normal letters — which is why platforms like X/Twitter that strip combining marks make them collapse back to plain text.
Why does any of this matter to you? Because once you think in characters, not fonts, you choose better: standalone-character styles (bold, italic, script, small-caps, fullwidth) paste reliably everywhere; combining styles are platform-dependent; and nothing you paste is ever a security risk — it’s just text. We even publish the full substitution map as an open CC0 dataset so anyone can see exactly which code points each style uses.