Line expansion is one of the basic geometric concepts in mathematics, which refers to the result of giving a finite line segment on a plane and extending it infinitely in two directions. Line expansion can be regarded as an infinite concept and plays an important role in geometry. The concept of line expansion originated from ancient Greek mathematics and is recognized as the basis of geometry.

Line expansion is widely used in mathematics, especially in the field of geometry. Many geometric theorems can be deduced by expanding a straight line. For example, the sum of the postulate of parallel lines and the plane angle is 180 degrees. In addition, in physics, linear expansion is also used to describe the properties of electrostatic field.

As a basic geometric concept, line expansion has been concerned by mathematicians since ancient times. In modern mathematics, line expansion is widely used in algebraic geometry, calculus, topology and other fields. At the same time, with the continuous development of computer science, line expansion is more and more widely used in computer graphics.