From Wikipedia:
If the space $X$ is sequential, we may say that $x ∈ X$ is a limit point of a subset $S$ if and only if there is an $ω$-sequence of points in $S - \{x\}$ whose limit is $x$; hence, $x$ is called a limit point.
I was wondering how an $ω$-sequence of points is defined? Is $\omega$ a special ordinal?
How is the limit of an $ω$-sequence of points defined?
Thanks and regards!