Every “fancy font” you've seen — 𝓱𝓮𝓵𝓵𝓸, ꧁ace꧂ — is not a font at all. Those are ordinary characters from the Unicode table, exactly like the letters in this sentence: text, not formatting.
Once you internalize that one fact, most mysteries solve themselves: why the style survives pasting, why some devices show boxes, why search can't find styled names, and why @handles refuse them.
A second alphabet inside the character table
Unicode is the global catalog that gives every character in every writing system a number. Around 2001 it added a full set of styled Latin letters for mathematical typesetting — bold, italic, script, outline and gothic each got A–Z and a–z, followed later by bubble, circled and squared decorations.
Those letters were meant for formulas, but because they look like a different typeface, they were borrowed for personal text. A generator does exactly one thing: swap each ordinary letter for the styled character at the same position. The text is identical; only the glyphs change.
Why the style survives every paste
Bold in a word processor is a formatting flag — it disappears when the destination doesn't support it. A styled letter simply IS bold: boldness is a property of the character, not the environment. Every place that accepts the text accepts the style.
It also explains counting: one styled letter is still one character (except strike/zalgo, where invisible combining marks are counted too).
Where the boundaries are
- Limited coverage: styled glyphs exist only for Latin letters and digits. Other scripts have no second form — Chinese nicknames use decorative frames instead.
- Search mismatch: styled characters aren't plain letters; verbatim search, @mentions and hashtags may fail.
- Display depends on fonts: a device without the glyph shows a box — see the boxes guide.
- Accessibility cost: screen readers may spell out the full character names. Never use for essential information.