Graphs are a pictorial representation of values and data and give a visual form to a large amount of information. The line graph helps in understanding the information quickly as using points connected by a line creates it. The graph is plotted along two axes: the x and y-axis, where the x-axis is known as the horizontal axis, and the y-axis is known as the vertical axis. Hence, the line graph is formed when points are joined together to display data that changes over time. The article gives a comprehensive overview of the line graphs, their examples, and how it shows values and brings information together.  

What is a line graph?  

The line graph is a chart that helps show the information that changes over time by plotting the values in linear form. The values are represented by points and hence connected by using straight lines. The graph consists of two axes, which are known as:

• x-axis, which is the horizontal axis
• y-axis, which is the vertical axis

The data in the graph is represented by joining various points, and lines connect these. The graph was first introduced by Nicolaus Samuel Cruquius, William Playfair, Francis Hauksbee, and Johann Heinrich Lambert.

What are the different types of line graphs?  

Here are majorly three types of graphs, and each of them has its characteristics.

• Simple line graph – The graph is the simplest, and it helps show the value through the form of a single line. Hence, it appears like a single line on the graph.
• Multiple line graph – The graph consists of more than one line plotted. Hence, it consists of multiple plotted lines showing different values.
• Compound line graph – The graphs are slightly complex because they contain various information. Hence, it is found that the graph is divided into more than two or more types of data. 

The vertical graphs consist of vertical lines which extend from each data point and down along the horizontal axis. Hence, when a line runs parallel to the y-axis, it is called a vertical line. Some of the common line graph examples include quarterly sales to identify trends in sales. 

Plotting the line graph 

The graph helps in connecting quantitative data between two changing variables, and hence the line is formed graphically by joining a series of successive data points. Hence, it helps compare two variables along the vertical and horizontal axis. The horizontal graphs are horizontal lines that extend from each data point and run parallel to the x-axis.

Here is the line graph where the plotted points join segments of straight lines in data. The function of the general linear function is in the form 

y = mx + c, where m and c are the constants. 

Hence, the linear graph can be drawn by using the following ways:

• Substitution of the two dissimilar values for the x by the equation y = mx + c, the value for the y is generated. Hence, it is easy to plot the points (x1, y1) and (x2, y2) on the line.
• Along both the axes, plot the horizontal and vertical lines. As followed by the plotting, plot two points on the Cartesian plane of the paper for a line graph. The two points are used in the line segment; it extends in two directions. 

Hence, the simple way to plot the graph is as provided below:

• The first step is to draw the x-axis and y-axis and write down the title along both axes to show the purpose of the graph.
• Take a line graph example where you want to plot a graph representing the earnings for five days. Hence, place the number of days on the x-axis and plot the earnings on the y-axis. Next is to label the axis as per all the factors.
• Once the values are put along both the axes, plot the exact values on the graph and join the points in the form of a line. 

Use of the Line Graphs

So, do we know what a line graph is? The graphs are used for easy interpretation of the values and hence make a comparison. Many applications use such graphs:

• It helps in showing the data which changes over some time. Hence. It helps with providing information about data and how it changes.
• It is largely used in many fields like medicine, science, engineering, mathematics etc., for representing the value of large amounts of data. 
• The line graph helps with tracking the change over a short and long period. Hence, it helps in comparing the changes between various groups over the same period. 
• It is better than other graph forms as it helps show and represent small changes in the system. 

 Conclusion 

The line graphs help show data information over some time when plotted along the x and y-axis. The values are plotted on the graph, and the dots are connected in the form of a line for presenting the data in numerical value. Hence, the line chart is a chart that has several points, which are the data, and these are connected in a straight line. Hence, the line graph example provides quantitative data between two changing variables with a curve or line and as it joins the series of the overall successive data points.