Definition:Limit Point/Topology/Set/Definition 5

Definition
Let $T = \left({S, \tau}\right)$ be a topological space.

Let $A \subseteq S$.

A point $x \in S$ is a limit point of $A$ if there is a sequence $\left\langle{x_n}\right\rangle$ in $A$ such that $x$ is a limit point of $\left\langle{x_n}\right\rangle$, considered as sequence in $S$.