Parallel line segments are any two line segments that run parallel to each other, which means that they will never cross. The length or thickness of each line does not matter.
In theory, all line segments are infinitely long. For practical purposes, people work with line segments, which are sections of the line. When there are two line segments, they can either be parallel to each other, perpendicular or neither. Parallel lines are always the same distance from each other. Perpendicular lines intersect each other at 90-degree angles. Finally, it is possible for lines or line segments to cross each other at an angle other than 90 degrees.