A line has one dimension: length.
They are designated by two points or a lowercase letter.
Two points determine a line.
A line indicates two opposite directions, as it can be viewed from left to right or from right to left.
Types of Lines
Two lines that meet at a point are called intersecting lines.
Two parallel lines do not intersect at any point.
Two straight lines are coincidental if all their points are common.
Two lines are perpendicular when they intersect at right angles (90º).
A ray or half-line is part of a line that is finite at one point and infinite in the opposite direction.