What Is a Point and a Line Segment?

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Let’s take a look at some funny drawings—we call them figures. The field of study that works with these drawings is called geometry. Before you can analyze the big, complicated, cool figures, it’s necessary to get a grasp on the simpler ones. The simplest figure of all is just a dot. We call it a point. In the image below you can see five such points.

Five points

When you have two points, you can draw a straight line through them. The part of the line that goes from one point to another is called a line segment. When a line segment is part of a figure, we often call it an edge or side.

In the image below you can see two points connected by a line segment. Next to it, there are three points, with three line segments drawn between them. In this case, the line segments are sides, and the figure they make up is called a triangle.

Five points with lines

When two line segments meet at a point, we call it a vertex or corner. In the picture above you can see that pairs of sides meet at each vertex.

Triangle with dots and lines

Think About This

How many vertices do you think you have in your bedroom?

Try counting them! Are there more vertices in other rooms in your house—or are they all the same? Can you find the room in your house that has the most vertices? Remember that vertices can turn both inwards and outwards.

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