What ⊿ means
⊿ is the right triangle. Unicode classifies it as a mathematical symbol and files it in the Mathematical Operators block; this site shelves it under Maths.
Its appearance depends on the font and text styling.
How it is encoded
⊿ is a single code point, U+22BF. In HTML that is ⊿, and in CSS \22BF.
Don't confuse it with
2Questions 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.
How to type ⊿
Windows (Word)
Alt+XType 22BF, then Alt+X to get ⊿.
Windows
Win+Rrun charmap for the full table, or use the emoji picker's Ω symbols tab (Win + .).
macOS
Control+Command+SpaceOpen the character viewer and search “right triangle”.
Linux
Ctrl+Shift+UType 22bf, then Enter or Space.
HTML
⊿CSS
\22BFCodes and encoding1 code points
HTML decimal
⊿
HTML hex
⊿
CSS content
content: "\22BF";
Each escape is closed by the next backslash; a trailing space is needed before a literal hex digit.
URL encoded
%E2%8A%BF
1
On screen
1
Code points
1
JS .length
3
UTF-8 bytes
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.