Bubble Chart is easy to understand : it is a chart describing data using bubbles / circle. The radius of the bubble – circle usually reperesents the measurement of the value of data.
Note : if the controls aren’t working, try use the ‘Data By’ control first, it should go back to normal. Sorry about the bug.
As a rule of thumb : the smaller the bubble – circle radius, the lesser the data value, the greater the bubble, the larger the value.
This visualization is describing the Growth Domestic Products of various nations around the globe.