Two charts can print identical candles on wildly different participation. One is a statement signed by a crowd; the other is an opinion whispered in an empty room. Volume — the number of shares or contracts that actually traded — is the difference, and it's the last dimension you need before chart-reading becomes three-dimensional: price, time, participation.
Reading volume: confirmation and divergence
The baseline habit is relative, not absolute: compare each bar's volume to its own recent average (the relative volume page formalizes this). Then apply the old confirmation logic, associated with volume analysts from Joseph Granville onward (paraphrase): healthy moves are fueled moves. A rally on expanding volume says new money agrees; the same rally on shrinking volume says the crowd is staying home, and the move is running on fumes. Breakouts (as the T4 course hammers home) are the classic application — a level can be crossed quietly, but it can only be defeated loudly, because defeating it requires absorbing everyone defending it.
Volume also marks where the business was done. Huge volume at a price means huge numbers of positions live there — memory, in Module 4's sense, freshly written. That intuition, pushed to its logical end, becomes the Market Profile course later in the track.
One caution before the folklore takes over: volume analysis is the area of charting with the most confident sayings and the least settled evidence. "Volume precedes price" is a hypothesis with famous supporters, not a law. Use volume as a weighting on your other evidence — the same candle at the same level counts for more with a crowd behind it — rather than as a standalone signal.
Gaps: the auction that jumped
A gap is a hole in the chart — today's range never touched yesterday's, because news or sentiment repriced the market while it was closed. The classic taxonomy (four kinds, detailed with real charts on the gaps page): the common gap, small and quickly refilled, statistical noise; the breakaway gap, which launches a move out of a base and often doesn't fill soon, because it marks genuine repricing; the continuation gap, mid-trend, the crowd piling into an established move; and the exhaustion gap, the last spasm of a mature trend, promptly reversed — the crowd's final latecomers buying the top.
Notice the four are defined by context (where in the trend structure they occur), which by this point in the course should feel familiar: nothing on a chart means anything by itself. "The gap fills" is a popular saying precisely because common gaps are common; assuming every gap fills is how traders end up fading breakaway gaps — arguing with genuine repricing.
Assignment
Return once more to your marked-up chart. Find the three highest-volume days of the year. For each, describe what price did that day (candle shape), where it happened (at a level? mid-air?), and what followed over the next two weeks. High-volume days are the chart's punctuation marks — learning to read them is learning where the crowd actually spoke.