Hi Richardo

On one hand you have someone who will buy at a particular price and, on the other, there's someone who will sell at that same price. In each case, one person is motivated to buy and the other to sell. How can one describe that transaction as a buy or sell? Since I am no expert at this, I decided to do the smart thing and look up someone who is. :>):>)

"Total volume is made up of buying volume and selling volume. Buying volume is the number of contracts that were associated with buying trades, and selling volume is the number of contracts that were associated with selling trades. However, this is often confusing for new traders because every trade requires both a buyer (a trader that is buying a contract) and a seller (a trader that is selling a contract). As every trade requires that a contract is being both bought and sold at the same time, it does not seem possible that a trade could be classified as either buying volume or selling volume.

The reason that it is possible to classify a trade as either buying volume or selling volume is based upon how the trade affects the current price. Every trade occurs at a single price, and with few exceptions, that price is either the bid price or the ask price. Volume that occurs at the bid price is known as bid volume. Bid volume is selling volume because it has the potential to move the price down, due to the bid price being lower than the ask price. Conversely, volume that occurs at the ask price is known as ask volume. Ask volume is buying volume because it has the potential to move the price up, due to the ask price being higher than the bid price. Therefore, trades that occur at the bid price are considered selling volume because they help the price move down, and trades that occur at the ask price are considered buying volume because they help the price move up."