The Volume Oscillator shows trends in the volume of shares that have been traded over a given period. It uses a Fast Moving Average (such as a 14 day/week MA) and a Slow Moving Average (such as a 28 day/week MA). The difference between the two moving averages is then plotted as a histogram. These settings can be adjusted in the Volume Oscillator settings modal.
Using the Volume Oscillator to confirm price trends: