∘
Ring Operator
- Unicode
- U+2218
- Category
- Math
- HTML Entity
- ∘
- CSS
- \2218
The ring operator (∘) is a mathematical symbol primarily used to represent function composition, where the output of one function becomes the input of another (such as f ∘ g). Visually, it looks like a tiny, hollow circle and sits distinctly lower than the standard degree symbol (°). Outside of advanced mathematics and logic, digital designers occasionally use it as a minimalist, lightweight bullet point or aesthetic text element.
How to Type
- Windows
- In Word: type 2218, then press Alt + X. Other apps have no standard Windows shortcut for it — copy it from this page
- macOS
- Control+Command+Space then search 'ring operator'
- Linux
- Ctrl+Shift+U then 2218
- HTML
- ∘ or ∘
In Programming
Commonly used in mathematical and computer science documentation to denote function composition. In LaTeX environments, it is generated using the \circ command.
Tags
LaTeX circ
U+2218
binary operator
circle
composition
composition operator
f composed with g
function
function composition
hollow circle math
math circle operator
mathematics
ring operator
ring operator vs degree symbol