A line segment is a part of a line that has two endpoints. It is defined by these endpoints, which can be labeled with letters, such as A and B. The length of a line segment can be measured, and it is always a finite distance, unlike a line that extends infinitely in both directions. In geometry, line segments are often used to represent distances and relationships between points. They can be combined to form shapes, such as triangles and rectangles. The concept of line segments is fundamental in various fields, including mathematics, engineering, and computer graphics.