Volume
Volume is the quantity traded over a period. It confirms the strength of a move: a breakout on high volume carries more weight than one without.
On stocks and futures, volume is real and centralised by the exchange. Forex has no central exchange, so platforms often show “tick volume”, the number of price changes, which roughly tracks real activity.
A rally with rising volume reflects genuine participation. A rally on falling volume suggests it is running out of steam. An extreme volume spike at the bottom of a sell-off can signal capitulation.
Tools such as volume profile or VWAP, used on indices and stocks, show at which prices most of the trading took place. Volume is always read relative to its own recent average, not as an absolute number.