What ［ means
It opens a fullwidth square-bracket pair. In Japanese quotations, ［…］ can hold a translator’s or editor’s addition, marking words that were not in the original. It can also mark a second bracket level when parentheses already contain one.
Accounts of the square bracket’s early history differ. One places it in Rafael Bombelli’s algebra manuscript around 1550; another credits François Viète’s 1593 mathematical book Zetetica. In mathematics, brackets grouped expressions. Japanese punctuation expanded under Western influence in Meiji print. In mixed East Asian encodings, fullwidth forms supplied two-cell counterparts to one-cell ASCII punctuation.
Why is ［ wider than [?
Its fullwidth shape reserves two display cells in East Asian text. The fullwidth and ASCII forms perform the same bracketing job but are distinct characters. In mixed East Asian encodings, the fullwidth form supports two-cell spacing alongside one-cell ASCII punctuation, keeping a line’s rhythm.
Formal, editorial and technical; it marks inserted structure rather than casual emotion.
For ordinary Japanese dialogue, use 「」; ［］ marks editorial or technical structure.
Part of collections
What it means when someone sends it to you
2 readingsAn editor’s or translator’s addition, not part of the original wording.
Don't confuse it with
2
Related characters
2
Combination ideas
3Questions people ask
1Why does ［ show as a box on some devices?
Because that device's fonts have no glyph for it. The character is still correct and still copies correctly — the box is a missing glyph, not a broken character.
More like this
10
Collections with ［
1
How to type or find ［
- Also called
- 角括弧 · かくかっこ · ブラケット
- Search it as
- bracket · square bracket · left bracket · fullwidth bracket
- Shows up in
- Anything that takes text · its shape is whatever your font draws
［\FF3BCodes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.