\begin{definition}[Definition:Orbit (Group Theory)/Length]
Let $G$ be a group acting on a set $X$.
Let $x \in X$.
Let $\Orb x$ be the orbit of $x$.
The '''length''' of the orbit $\Orb x$ of $x$ is the number of elements of $X$ it contains:
:$\size {\Orb x}$
Category:Definitions/Group Actions
\end{definition}