Algebra
《Algebra》 · 第 88-89 页 · Chapter II，Section 4「The Action of a Group on a Set」，Examples
Let $H$ be a subgroup of a group $G$. An action of $H$ on the set $G$ is given by $(h,x)\mapsto hxh^{-1}$; to avoid confusion with the product in $G$, this action of $h\in H$ is always denoted $hxh^{-1}$ and not $hx$. This action of $h\in H$ on $G$ is called conjugation by $h$.