Scatter plots are a method of graphically displaying bivariate data.
Example bivariate data is displayed below. Our two variables are age and yearly income.
What is the relationship between age and yearly income?
The relationship can be plotted on a scatter plot. Below, age is on the x-axis, while yearly income is on the y-axis:
Just by looking at the graph, it would appear that as age inceases, yearly income increases. It is a fairly good bet that our variables are related.