Full-width / Half-width
When Latin letters go square.
Where it came from
In Chinese, Japanese and Korean (CJK) typography, every character occupies a square "full-width" cell. Mixing in Latin text looked ragged, so Unicode added full-width versions of A–Z, 0–9 and punctuation — each as wide as a CJK glyph.
There are also half-width katakana for the reverse direction. These ranges exist mainly for compatibility with legacy encodings like Shift-JIS.
How it works
Full-width A (U+FF21) is the visual twin of ASCII A (U+0041) but twice as wide. Converting is a fixed code-point offset within the compatibility blocks.
UWC switches text between full-width and half-width forms in your browser — useful for normalizing CJK documents or fixing copy-paste artifacts.