Underline text with real characters: single line, double line, or an overline above the text instead.
| Input | Output |
|---|---|
| underline (Underline) | u̲n̲d̲e̲r̲l̲i̲n̲e̲ |
| important (Double underline) | i̳m̳p̳o̳r̳t̳a̳n̳t̳ |
| heading (Overline) | h̅e̅a̅d̅i̅n̅g̅ |
Use it for clarity in plain text where formatting is unavailable: important terms in a note, a heading in a chat message, or a form label. Double underline is the traditional proofreading mark for emphasis, and the overline alternative gives a bar above the text.
A single underline marks emphasis, a double underline marks stronger emphasis — the convention comes from proofreading, where two lines mean 'this really matters'. Both are just different combining marks (U+0332 and U+0333).
The position is decided by the font that draws the base character, not by the mark. Different fonts, different sizes and fallback glyphs all place the line at slightly different heights, which is why a mixed-font sentence can look uneven.
Yes — this tool adds the mark after every character including spaces, which is what you want for a continuous line under a phrase. Turn it off and the line breaks between words.
Most services reject combining marks in handles and display names. Where they are accepted, the name can look broken in other people's apps, so keep this style for text you control.