A depth chart visualizes the displayed liquidity in an order book. It commonly plots price horizontally and cumulative order quantity vertically, with separate curves for bids and asks. It shows current offers to trade, not a history of completed volume.
Reading cumulative quantities
On the ask side, quantity accumulates from the lowest ask toward higher prices. Suppose three tokens are offered at $10 and seven at $11. The cumulative sell quantity through $11 is ten tokens; this does not mean all ten are offered at $11.
On the bid side, quantity accumulates from the highest bid toward lower prices. A large step in either curve can indicate a concentration of orders, often described as a buy or sell wall.
What the view leaves out
Check the quantity unit, price grouping and zoom level. A chart can display token amounts or value, and grouping nearby prices can change how large a wall appears. The view is also specific to its venue and trading pair.
Orders can be cancelled, replaced or filled before a new trade arrives. Hidden quantities may be absent. A deep-looking curve therefore does not guarantee execution at the displayed prices or prove future support or resistance.