Volume by Price is an excellent indicator combining both price and volume into one tool. The volume of trades is plotted onto the chart horizontally at price intervals. Volume by Price can be used to see which prices invoke the most volume and activity.
This is useful in determining where the majority of historical trading volume occurred and help find meaningful support and resistance lines. Volume by Price can also help in picking price changes or reversals. A price change is usually associated with large volume so if the current price is hovering around a level of high volume expect a price direction change. Likewise, low volume can be associated with times of uncertainty or consolidation.
Remember, this is a very subjective measure. Volume by Price is never sufficient in and of itself to plan trades.