Line segment

Imagine you have a long stick. Now, cut that stick into two pieces so that you have two shorter sticks of different lengths. These shorter sticks are called line segments. They still have the same shape as the long stick, but they are now shorter and have a definite end point on each side.

So, a line segment is like a part of a long line that has been cut and has a start and end point. Just like when you draw a picture and highlight something with a colored marker, you can use a line segment to mark a specific part of a line that you want to focus on.