∈
∈ Element Of Symbol
The element-of symbol (∈) says a thing belongs to a set: x ∈ A means x is a member of A.
Also known as: element of symbol, member of symbol, belongs to symbol, is in symbol.
Codes
| Symbol | ∈ | |
| Not an element of | ∉ · U+2209 | |
| Unicode | U+2208 | |
| HTML entity (named) | ∈ | |
| HTML entity (decimal) | ∈ | |
| HTML entity (hex) | ∈ | |
| CSS | \2208 | |
| LaTeX | \in | |
| Windows Alt code | Alt + 8712 |
How to type ∈ (Element Of Symbol)
Windows2208, Alt + X
In Word, type 2208 then press Alt + X. Elsewhere, copy ∈ above or use Character Map (search “element of”).
Mac
No default keystroke. Open Character Viewer (Control + Cmd + Space) and search “element of”, or copy ∈ above.
Microsoft Word2208, Alt + X
Type 2208, then press Alt + X to convert it to ∈.
Google Docs
Insert → Special characters, then search “element of”. In an equation, \in followed by a space also works.
LaTeX\in
Use \in in math mode: x \in \mathbb{R}. \notin gives ∉, and \ni gives the reversed ∋.
Usage
- x ∈ A reads “x is an element of A” or simply “x is in A”. Its negation is ∉ (U+2209): 0 ∉ ℕ under the convention where the naturals start at 1.
- It is the workhorse of set-builder notation: { x ∈ ℝ | x > 0 } is “the set of real x such that x is positive”.
- ∋ (U+220B) is the same relation read backwards — A ∋ x, “A contains x”. It is rare, and mostly used to keep a sentence's subject in front.
- Which one to use: ∈ (U+2208) is the set-membership relation. It is not the Greek letter epsilon ε (U+03B5), though the shape comes from one — Peano chose it for the Greek ἐστί, “is”. Typing ε where ∈ belongs will typeset with the wrong spacing and fail to match a search.