The volume is is primary. There are three types of volume:
Tick volume-shows quantity of contracts or shares that entered the market for 1 tic.
Quantitative - shows quantity of made transactions for the certain period of time.
Pure volume - shows quantity of contracts or shares bought or sold for the certain period of time for a
determined price.
Pure volume is indicator for interest of the market in some prices, that allows to open position and close it.
An exchange still long since played a role volume. Indexes, beans, metals, currencys, shares-everything trades by
volumes got from stock exchange.For example: on one price a turn-over of money is bigger than on other prices- that
means this price is a level for us to open position from it.