How can a line of best fit be useful?

It is very useful and interesting to be able to enter data for two variables, graph those points in a scatter plot, and then generate a line of best fit through those points. From the line of best fit, it is fairly simple to generate a linear equation. A line of best fit is drawn through a scatterplot to find the direction of an association between two variables. This line of best fit can then be used to make predictions.