Which of the following is NOT a characteristic of a line?

A line is defined as a one-dimensional figure that has no thickness and extends infinitely in both directions. This fundamental definition highlights that a line cannot have endpoints; instead, it is composed solely of an infinite series of points all aligned in the same direction.

The characteristics that define a line include extending infinitely in both directions and being made up of points; these are foundational properties in geometry. Additionally, lines can intersect with other lines, forming various angles and geometric relationships. However, the presence of definite endpoints is characteristic of line segments, not lines. Therefore, identifying that a line has no endpoints is crucial to understanding its definition and distinguishing it from other geometric figures.