A normal candle tells you the open, high, low and close but hides how the volume was distributed and who was aggressive. A footprint chart, also called a cluster or bid/ask chart, opens the candle up and prints the traded volume at each individual price, split by whether it happened at the bid or the ask.
What a footprint shows
Each footprint bar is a vertical stack of price levels, and each level displays two numbers: the volume that traded at the bid (aggressive selling) and the volume that traded at the ask (aggressive buying). Reading a footprint, you are no longer guessing whether a green candle had real buying behind it — you can see, price by price, how much was bought aggressively versus sold aggressively. This turns a single candle into a detailed map of the auction that built it. It is the most information-dense view of order flow available on a chart, and it is why professional futures traders live on footprints.
Reading bid vs ask volume
By convention, volume traded at the ask (buyers lifting offers) is shown on one side and coloured green, while volume at the bid (sellers hitting bids) is on the other side and coloured red. A price level where the ask volume dwarfs the bid volume means aggressive buyers dominated there; the reverse means sellers did. You read a footprint by scanning for where one side overwhelmed the other and where the heaviest volume printed. The point is not the raw candle colour but the internal balance of aggression, which frequently disagrees with what the candle alone suggests.
Delta: the net of the fight
Delta is simply ask volume minus bid volume — the net aggression for a bar. A large positive delta means aggressive buyers outweighed aggressive sellers; a large negative delta means the opposite. The Δ number printed under each footprint bar in the diagram is this net. Delta usually rises with price and falls with price, which is unremarkable. The interesting information is when they disagree: a bar that closes higher but prints shrinking or negative delta, like the last bar in the diagram, warns that the up-move is being driven by fading aggression and may be running out of buyers.
The point of control
Within each bar, the price level that traded the most total volume is that bar's point of control, marked by the purple bar in the diagram. It represents the price the auction spent the most effort at — the fairest value for that bar. Rising points of control from bar to bar confirm an orderly trend; a point of control that jumps around erratically signals a disorganised, choppy auction. Watching where the point of control forms within a bar (near the high, middle or low) tells you where the bulk of business was actually done, which is often more meaningful than the close.
Imbalances and stacked imbalances
An imbalance occurs when the volume on one side of a level massively exceeds the other, conventionally by 3-to-1 or more, comparing diagonally (the ask at one price against the bid at the price below). A single imbalance is noise; several imbalances stacked consecutively — the bold-outlined cells in the diagram — show sustained, one-sided aggression and often mark levels that act as support or resistance on a retest. Stacked buy imbalances beneath a rising market are a footprint bull's confirmation; stacked sell imbalances above a falling one confirm sellers. They are among the most actionable footprint signals because they pinpoint exactly where aggression concentrated.
Putting it together: absorption and exhaustion
The real power of footprints is spotting when aggression fails. Absorption is heavy aggressive volume at a level that does not move price — buyers keep lifting the offer but price will not rise because a large passive seller is absorbing every market order. Exhaustion is the tail end of a move where delta spikes but price barely advances, showing the last aggressors piling in with no one left to continue. Both appear vividly on a footprint as large volume with no corresponding price progress, and both frequently precede reversals. Learning to see effort without result is the footprint reader's edge.