A line graph is a graph that represents a trend of the dataset with a line. At least two numeric variables are mandatory to draw a line graph. On an X-Y plane, both numeric-variables mark a point, and the line that forms by the combination of all these marked points shows the trend of our dataset.
Why do you need it?
We need a line graph to visualize if a company is going in profit or a loss, and many other similar instances. We can add different lines for various categories/companies with distinguishing color, to compare categories/companies visually on the same timeline in terms of profit.
What kind of data you can visualize with it?
A line chart best suits data that is time-related. If you have a dataset that contains days of a week and profit of sales for every day, then you can easily plot a line graph with it. If the line graph shows upward movement, then the company spells out a profit, and if movement declines, then there is a clear loss.