Buying volume is the number of shares, contracts, or lots that were associated with buying trades, and selling volume is the number that were associated with selling trades. This concept is indeed confusing because every trade requires both a buyer and a seller of the given asset. However, you can distinguish buying volume from selling volume based on whether a transaction occurs at the bid price or the ask price. That is why they are often not the same in e.g. a day.
Reply To: Trading Volume : Red/Gray Bar IndicatorsChristiaan Vlasblom2020-11-02T09:24:46-06:00