Step-by-step explanation: To understand what a line segment, we first need to introduce the most basic figure in geometry which is called a point. A point in usually labeled with a capital letter. For example, .A.
When we have two points such as points X and Y, we can introduce our next figure in geometry which is called a line segment. For example, segment XY. A line segment is defined as a figure that's composed of two points which are called the endpoints and all the points in between.
Segment XY can be represented as XY with a segment drawn over it like I have attached in in the image provided.