Volume of Trade, Definition
The number of contracts traded during a specified period of time. Volume represents the the extent of trader participation in the market. Volume can be measured for a single security or for an entire exchange, such as the NYSE. When a rise in price is accompanied by rising volume this confirms the trader participation in the move and serves as a confirmation of the validity of the move. Beware of dramatic volume spikes that are not accompanied by fundamentals supporting the move.
See also: On Balance Volume