Straight objects (i.e., having no curvature) with negligible width and depth.
- In geometry, the notion of line or straight line was introduced by ancient mathematicians to represent straight objects (i.e., having no curvature) with negligible width and depth.
- Lines are an idealization of such objects, which are often described in terms of two points or referred to using a single letter.
- Until the 17th century, lines were defined as the first species of quantity, which has only one dimension, namely length, without any width nor depth, and is nothing else than the flow or run of the point which will leave from its imaginary moving some vestige in length, exempt of any width.
- The straight line is that which is equally extended between its points.