What is this indicator?
Works similarly to RSI but factors in trading volume as well as price in its calculation. For this reason it's sometimes called a “volume-weighted RSI.”
How to read the chart
A rise happening alongside price movement confirms that move's validity; a divergence between volume and price is often a sign of a weakening trend.
Practical tip
Always check volume alongside price movement; volume on its own, without regard to the price trend, isn't a reliable signal.