A bubble chart is also similar to an XY chart. Data points are scattered through the chart area, displayed on locations whose coordinates are calculated with respect to the xy values. Different from the other types of scatter charts, bubble series are assigned a third variable, which determines the diameter of each bubble displayed. Therefore, each data point is in fact associated with three variables, two of them determining the bubble location and the third one determining the bubble diameter.
Tooltips popup if mouse cursor hovers over any bubble, displaying related xyz values.