Four kinds of Unicode bold
| Style | Letters | Digits | Feel |
|---|---|---|---|
| Bold | A to Z, a to z | 0 to 9 | Classic, bookish |
| Bold Sans | A to Z, a to z | 0 to 9 | Clean, modern, matches most app interfaces |
| Bold Italic | A to Z, a to z | Stay plain | Emphatic |
| Bold Italic Sans | A to Z, a to z | Stay plain | Sporty, modern |
All four are complete for letters, so there are no odd-looking exceptions. They come from the Mathematical Alphanumeric Symbols block and are among the best supported styled characters on current devices.
Use bold for emphasis, not whole paragraphs
Bold works because it is rare. A bold first line, a bold call to action, or a bold product name catches the eye. A whole bold caption just looks loud and becomes harder to read.
When real bold formatting is better
If the app you are writing in has a bold button or supports Markdown, use that instead. Real formatting keeps your words searchable, translatable, and readable by screen readers. Discord, for example, supports **double asterisks** for bold in messages, which is better than Unicode bold for chat.
Unicode bold is the right tool for places that strip formatting: profile bios, display names, post captions, comment boxes, and many short text fields.
Accessibility note
The Unicode Consortium notes that these mathematical letters are not meant to replace styling markup. Some screen readers may announce each letter by name, such as โmathematical bold capital Sโ. For anything important, such as dates, prices, or instructions, keep a plain version. More tips are in fancy text and accessibility.