Volume is the total quantity of shares which have transacted in a given time frame. Traders use volume as a measure of a stock’s volatility or potential volatility. Higher volume will generally signify that a lot of parties are interesting in trading the stock, and the stock is likely to move as a result. Volume measurements are also used as a signal of liquidity of a security, so a trader can judge his ability to enter or exit a position at current market values.
Higher volumes are generally favorable to traders, but may only be beneficial to a point, or may not be beneficial depending on the exact strategy. A trader may also look at average volume at a daily level, or may even break this down in smaller increments of the day to judge when he may best employ a strategy.
Volume does not double count transactions, meaning if a trader purchases 100 shares from another seller it results in 100 shares of volume, not 200.
Typically in charting software volume is displayed below the price chart. Volume is normally displayed for every price bar, so that if a chart is displaying 1 minute price bars volume will display for each minute. The chart and volume together typically will look something like this:
This is a daily chart of GE, with the volume displaying for each price bar directly below the bar. In general it can be noted that days with lower volume also have a smaller range in price.
Volume is NOT an indication of price direction by itself, it simply is a signal that traders use to judge if a stock is likely to move. Often times traders will watch screens displaying the stocks with the highest volumes, or displaying sudden spikes in volume, which is can be a sign that news was released, or at least that the stock will be moving.
Traders who are relatively new and are working on refining their strategy will be well served to watch how volume impacts trading.