Definition 2.15

Definition 2.15: Let $$A$$ be a subset of some topological space $$X$$. Then we say a point $$p$$ in $$X$$ is a limit point of $$A$$ if every open set in $$X$$ that contains $$p$$ also contains a point of $$A$$ different from $$p$$. (Note that a limit point of $$A$$ need not necessarily be an element of $$A$$.)