Horizontal – Definition with Examples

What is Horizontal?

What do you see?

objects standing vertically

There is a standing line, a standing screwdriver and a vertical thermometer. 

What do you see now?

objects lying  horizontally

There is a sleeping line, the screwdriver lying flat on the floor and the thermometer placed on the floor. 

What you see is described as a HORIZONTAL position or objects placed horizontally. 

A sleeping line is nothing but a horizontal line.

A screwdriver lying flat is the same as a ladder lying horizontally.

A thermometer lying flat on the floor is the same as a man lying horizontally on the floor.

Horizontal is the opposite of vertical. In geometry, we use the words vertical and horizontal for standing and sleeping respectively.  

The line at which the earth’s surface and the sky appear to meet is called the horizon. Anything parallel to the horizon is called horizontal. 

horizontal line visual example

As vertical is the opposite of horizontal, anything that makes a 90-degree angle (right angle) with the horizontal or the horizon is called vertical. 

horizontal line is one that runs across from left to right

So, the horizontal line is one that runs across from left to right. 

Use of horizontal and vertical in Mathematics

  • We add and subtract horizontally and vertically.

Example 1:

Add 24 and 33 horizontally and vertically.

$24 + 33 = 57$  $24+ 33 = 57$

Example 2: We also make horizontal and vertical bar graphs.

                                            Horizontal Bar Graph

horizontal bar graph

 Example 3: Vertical Bar Graph

Horizontal – Definition with Examples

Example 4: We use horizontal and vertical lines in geometry and art too. 

abstract art of horizontal lines and vertical lines

What is a Horizontal Line?

Imagine you have a paper, and someone asks you to draw a line. What all possibilities do you think will cross your mind? Well; there are a few ways you could do this.

If you were bored; you would most probably just end up drawing a random motion like this; called a skew line.

a line drawn on a paper using a pencil

And if you wanted to think like a mathematician or an artist; you would imagine a tree or something standing and draw a line top to bottom like this; called a vertical line.

vertical line drawn on a paper

Or you could think of a car or something lying down and sketch your line from left to right like this; called a horizontal line.

horizontal line drawn on a paper

A horizontal line is a sleeping line. It is a straight line that goes from left to right or right to left. The word horizontal is derived from the word “horizon” which is the line where the earth and sky appear to be meeting far far away. 

Horizontal Lines around Us

We see horizontal lines all around us in shapes, objects, figures, and drawings. 

Here are some examples of horizontal lines. 

Horizontal lines in objects:

objects having horizontal lines

Horizontal lines in Math:

Horizontal lines are the building blocks of so many 2D and 3D shapes in elementary geometry. Squares, Triangles, Rectangles, Cubes, Trapezoids, Prism are just some basic examples of shapes where we can observe horizontal lines.

horizontal lines in math

Horizontal lines in Coordinate Plane

In coordinate geometry, horizontal lines are defined as lines parallel to the x-axis. If two points on a line have the same y-coordinate points then the line is said to be horizontal.

In the given image AB is a horizontal line parallel to the x-axis and if you observe carefully the y-coordinate of both points A and B are the same. Another interesting this to note about the horizontal lines is that they are always perpendicular to the vertical lines.

horizontal lines on a coordinate plane

Drawing a Horizontal Line

Using a Ruler:

To draw a horizontal line using a ruler, keep the ruler in sleeping position, parallel to the edge of the page and draw the line from left to right or right to left. 

drawing a horizontal line using a ruler and a pencil

To draw a horizontal line on a coordinate plane

Follow these steps

  • Plot any point on the coordinate plane, for example, (1, 2).
  • Identify the y-coordinate of the point marked. Here, it is 2.
  • Plot another point on the coordinate plane such that its y-coordinate is the same as the previous point plotted. For example, (–5, 2).
  • Join the two points plotted using a ruler to get a horizontal line. 
drawing a horizontal line on a coordinate plane

Uses of Horizontal Lines

Horizontal lines are used in symmetry and photography. 

A horizontal line of symmetry runs across the image from left to right (or vice versa) and divides the image into identical halves. 

horizontal lines of symmetry

Cameras are designed to take photographs in landscape (horizontal) or portrait (vertical) mode. In horizontal mode, photographs are wider than they are tall. In vertical mode, photographs are taller than they are wide. Our eyes see the surrounding horizontally giving a wider view instead of taller.

horizontal mode or landscape mode in photography
horizontal mode or landscape mode in photography

Horizontal Line and Vertical Line

Horizontal LineVertical Line
It is a sleeping line that goes from left to right or vice versa. It is a standing line that goes from top to bottom or vice versa.
It is parallel to the x-axis. It is parallel to the y-axis.
It is perpendicular to the y-axis.It is perpendicular to the x-axis. 

Fun Facts

The word horizontal originated in the mid 16th century from modern Latin horizontal, from the late Latin horizon.

Solved Examples 

Example 1: Which line segments represent horizontal lines?

a square


Lines BC and AD are horizontal lines.

Example 2: Identify the lines indicated by the arrows in each of the following shapes.

identifying a horizontal line


  1. Horizontal line
  2. Vertical line
  3. Horizontal line
  4. Vertical line

Example 3: Identify the horizontal lines in the given shape.

identifying horizontal lines in a shape


AB, EF, and CD are the horizontal lines in the given shapes.

Example 4: Name five English alphabets that have horizontal lines.


E, F, H, L, T

Practice Problems

Horizontal - Definition with Examples

Attend this quiz & Test your knowledge.


Which one of the following is the horizontal line?

Horizontal – Definition with Examples
Correct answer is: a
A horizontal line is a sleeping line.
Horizontal – Definition with Examples

How many horizontal lines does the given figure have?

Horizontal – Definition with Examples
Correct answer is: 3
There are 3 straight lines that go from left to right or right to left
Horizontal – Definition with Examples

At what time the minute hand of a clock will be horizontal?

12 o’clock
Quarter past 12
Half past 12
12:40 pm
Correct answer is: Quarter past 12
At a quarter past 12 minutes hand will be at 3. So, the minute hand will be horizontal.

Frequently Asked Questions

A horizontal line is a straight line that is parallel to the x-axis and where all the points on the line have the same y-coordinate.

Yes, all horizontal lines are parallel to each other. Horizontal lines when extended also never intersect with one another.

Horizontal lines are lines that run from left to right and are parallel to the x-axis. Vertical lines are lines that run up and down and are parallel to the y-axis.