A volume profile plots traded volume horizontally against price rather than against time. This reveals the price levels where the most trading took place, highlighting zones of heavy activity and zones that were passed through quickly.
The price with the highest traded volume is often called the point of control, and the broad area containing the bulk of volume is the value area. These reference points show where participants have done the most business and, by extension, where significant interest may sit.
Volume profiles are used to add context to price levels: high-volume zones can act as areas of interest, while low-volume gaps may see faster movement. The profile summarizes historical activity and is a descriptive tool, not a signal to act.