# Line Segments - Concept

###### Explanation

A line segment is part of a line, has fixed endpoints, and contains all of the points between the two endpoints. One of the most common building blocks of Geometry, **line segments** form the sides of polygons and appear in countless ways. Therefore, it is crucial to understand how to define and correctly label line segments.

###### Transcript

If you had a line -- so if I drew in

arrows which says that they're going

infinitely, and you pick two points on

that line and you said that, wait

a minute, I'm way concerned about the

points that are in between these

two points right here, you would

be creating a line segment.

So line segment is only part of a line,

and it has fixed end points.

And by definition the line segment contains

all the points that are in between

your end points.

So to be more specific, if we had this line

segment right here, A and B, A and

B are your end points.

So I'm going to draw the arrow right there

and write that these are my end points.

And the end points are important because

that's how we label this line segment.

So we're going to call this line segment

A, B and notice I drew a little line

on top of A and B with no arrows which

tell you, the geometry student,

that this is a line segment A, B that

only goes from point A to point

B and contains all the

points in between.