Element Of in LaTeX (\in)

Where it is used

States membership: the element on the left belongs to the set on the right.

\in is the basic set-membership relation, as in x \in \mathbb{R} or n \in \mathbb{N}, and it gets relation spacing. Its mirror \ni reads "contains as an element", and \notin negates it. Do not confuse it with \epsilon or \varepsilon, which are Greek letters that look similar but have different spacing and meaning. In sums and set-builder notation it binds the index, as in \sum_{x \in S} f(x) or \{x \in X : f(x) > 0\}. For subset relations between two sets use \subseteq, not \in.

Also listed under: Set Theory, Quantifiers

Minimal compilable example

Paste this into an empty .tex file and compile it with pdfLaTeX, XeLaTeX or LuaLaTeX.

\documentclass{article}
\usepackage{amssymb}
\begin{document}
Element Of: $\in$

\[ \{x \in \mathbb{R} : x^2 < 1\} = (-1, 1) \]
\end{document}

Related symbols

• Not Element Of\notin
• Exists\exists
• Subset\subset
• For All\forall
• Union\cup
• If and Only If\iff

Frequently asked questions

How do I write Element Of in LaTeX?

Type \in in math mode, for example $\{x \in \mathbb{R} : x^2 < 1\} = (-1, 1)$. It works in plain LaTeX without loading any package.

Which package do I need for \in?

None. \in is part of standard LaTeX, so it compiles with nothing in the preamble but the document class.

Can I use \in in text mode, or only in math mode?

Only in math mode. Outside $...$ LaTeX stops with "Missing $ inserted", so write $\in$ in running text. If you only need the glyph in text, paste the Unicode character ∈ instead (with XeLaTeX or LuaLaTeX and a font that has it).