In geometry, a “line” is a straight path that extends infinitely in both directions. It is defined by two points and contains all the points that lie between those two points. A line has one dimension, which is length. Lines are a fundamental element in geometry and have various properties, such as being perfectly straight and having no thickness. They are used to describe the shortest distance between two points and play a crucial role in understanding shapes, angles, and spatial relationships in mathematics and the physical world.