Volume is usually displayed as a bar graph along the bottom of a price chart, or on a separate chart to be viewed in conjunction with a simple price chart. Obviously time is plotted along the X-axis and volume on the Y-axis (though the volume scale is often not shown).
Example

Click here for the full size graph.
There are two accepted ways of displaying the volume of shares traded. The first is a relative level of volume which is 'zero based'. This means that the bottom of each volume bar is at the zero level.
The second, which most technical analysts prefer, is that of 'relative adjusted' volume. This is created by subtracting the lowest volume that occurred during a trading period from all of the volume bars. So instead of the bottom of the bar representing zero it is a real figure equal to the lowest volume traded. This makes it easier to see trends in volume and monitor changes in behaviour by taking away the bulk of the 'normal' volume.


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