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U+FEFF · Arabic Presentation Forms-B

Byte Order Mark (Zero Width No-Break Space)

U+FEFF is best known as the byte order mark (BOM): an invisible character at the very start of a file that signals UTF-16 byte order or identifies a file as UTF-8. Its original role as a zero width no-break space in the middle of text is deprecated in favor of the word joiner.

UnicodeU+FEFF
HTML
U+FEFF

Character codes

Unicode code pointU+FEFF
Decimal65279
HTML (hex)
HTML (decimal)
CSS\FEFF
JavaScript\uFEFF
Python\uFEFF
UTF-8 bytesEF BB BF
UTF-16FEFF
URL-encoded%EF%BB%BF

Character details

Official nameZERO WIDTH NO-BREAK SPACE
Unicode blockArabic Presentation Forms-B
General categoryFormat Character (Cf)
SymbolHero categorySpaces & Invisible Characters
EmojiNo

How to type the Byte Order Mark (Zero Width No-Break Space)

Windows

  • In Microsoft Word or Outlook: type FEFF then press Alt + X.
  • Open Character Map (search “Character Map” in Start), tick “Advanced view”, search for “zero width no-break space”, then Select and Copy.

Mac

  • Press Control + Command + Space to open the Character Viewer, search “zero width no-break space”, and double-click the result.
  • With the Unicode Hex Input keyboard enabled (System Settings → Keyboard → Input Sources), hold Option and type FEFF.

iPhone & Android

  • Tap Copy at the top of this page, then long-press where you want it and choose Paste.

Docs & web

  • Google Docs: Insert → Special characters, then search “zero width no-break space” or enter U+FEFF.
  • HTML: 
  • Excel / Google Sheets: =UNICHAR(65279)

Examples

  • A text editor saving a CSV file as "UTF-8 with BOM" so older spreadsheet apps detect the encoding
  • A UTF-16 file starting with the BOM so software knows whether bytes are big-endian or little-endian
  • A stray BOM at the start of a PHP or JSON file causing unexpected output or parse errors

Good to know

Don’t mix it up: It is often confused with the zero width space U+200B and the word joiner U+2060, which are the correct choices for invisible break control inside text.

Tip: If a script or config file fails because of strange characters at the start, re-save it as UTF-8 without BOM.

Display: the character itself is always the same code point, but its shape comes from the font on the device showing it. If you see an empty box, the font lacks this glyph—the text is still correct.

Guides

Why Symbols Show Up as Boxes or Question Marks Zero-Width Space: What It Is and How to Use It

Similar spaces & invisible characters

Non-Breaking Space
Soft Hyphen
En Space
Em Space
Thin Space
Zero Width Space
Zero Width Non-Joiner
Zero Width Joiner
Word Joiner
Ideographic Space
Space
En Quad
Em Quad
Three-Per-Em Space
Four-Per-Em Space
Six-Per-Em Space
Figure Space
Punctuation Space
Hair Space
Narrow No-Break Space
Medium Mathematical Space
Function Application

See all 26 spaces & invisible characters →

Questions

What is the Unicode for the Byte Order Mark (Zero Width No-Break Space)?

It is U+FEFF (ZERO WIDTH NO-BREAK SPACE), decimal 65279.

Is there a Windows Alt code for it?

No standard Alt code exists for this character. In Word type FEFF then Alt+X, or copy it from this page.

How do I type it on a Mac?

There is no built-in Option shortcut. Use the Character Viewer (Control + Command + Space) and search “zero width no-break space”, or copy it from this page.

What is the HTML code?

Use the numeric reference  (or ). There is no named entity.