Alex Velez describes the nature of the scatterplot:
A scatterplot is a niche chart, but it’s one of my favorites! If you are a statistician or work in a technical field, a scatterplot might be your go-to graph type. However, if you don’t perform a lot of statistical analysis, then these charts may be unfamiliar. Regardless of your current comfort level, scatterplots are extremely useful to focus on the relationship between two series—a scenario that is common in both technical and non-technical fields. Let’s explore some of the basics of scatterplots via an example; I’ll also cover tips for designing more effective ones and discuss common variations (bubble charts, connected scatterplots, etc.), too!
Read on for a good explanation of what scatterplots are, variants on the theme, and when they make sense to use.