A line segment is a part of a line that has two distinct endpoints. It is the shortest distance between these two points and can be measured in units such as centimeters or inches. Unlike a full line, which extends infinitely in both directions, a line segment is finite and has a specific length. In geometry, line segments are often used to form shapes and figures, such as triangles and rectangles. They are represented visually as a straight line with dots at each end to indicate the endpoints. Understanding line segments is fundamental in studying other geometric concepts, including angles and polygons.