Line Segment

A closed interval corresponding to a Finite portion of an infinite Line. Line segments are generally labeled with two letters corresponding to their endpoints, say $A$ and $B$, and then written $AB$. The length of the line segment is indicated with an overbar, so the length of the line segment $AB$ would be written $\overline{AB}$.

Curiously, the number of points in a line segment (Aleph-1) is equal to that in an entire 1-D Space (a Line), and also to the number of points in an $n$-D Space, as first recognized by Georg Cantor.

See also Aleph-1, Collinear, Continuum, Line, Ray