A bubble chart uses three variables to represent data points in the form of bubbles. The first two variables help to plot the data on the X-axis and the Y-axis, respectively. The third variable indicates the size of the bubble. Each point in this chart is a category disparate to a scatterplot.
Why do you need it?
We need a bubble plot to visualize our irregular and untidy data, making it effective in grasping, each data category in just sight. The area of bubbles in this chart is proportional to the data of that category, which the bubble represents. We should always use bubble charts only when there are fewer categories, or else the plot will become bulky.
What kind of data you can visualize with it?
A bubble plot is good for three variable data. Assume you have a dataset in which two variables are GDP and life expectancy at birth, respectively, which we use to plot the bubbles on the X-Y plane. A third variable that is population gives size to the bubble, and additionally, the color of the bubble can visualize the continents.