A trader coming from equities carries an assumption so basic it is invisible: that somewhere there is a resting order, and price is where two of them meet. Remove that and most intuitions about liquidity stop working.
An automated market maker holds a reserve of two assets and quotes a price derived from their ratio. The common design keeps the product of the two reserves constant: trade one in, take the other out, and the ratio — and therefore the price — moves. Nobody decided the new price. It fell out of the arithmetic.
Three consequences that matter
Every trade moves the price. Not just large ones. There is no resting size at a level to absorb you, so the move is continuous and begins at the first unit. What feels like a spread is really the price impact of your own order — covered properly in slippage and price impact on-chain.
Depth is a curve, not a ladder. On a book you can read available size at each level. In a pool there are no levels; there is a single continuous function, and the only meaningful question is how much price moves for the size you actually want to trade. This is why quoting “liquidity” as one number is close to meaningless without saying at what size.
The pool never refuses. An order book can empty. A constant-product pool will always fill you, at a price that approaches infinity as you drain the reserve. There is no halt and no gap — just a quote that gets arbitrarily bad, which is a very different failure mode from a market that stops.
Who supplies it, and why they leave
The reserves belong to liquidity providers who deposited both assets. They earn a share of trading fees, and they carry an exposure that has no equity analogue — the pool automatically sells the asset that is rising and buys the one that is falling. That is the mechanism behind impermanent loss, and it is the reason depth can vanish from a token that is doing nothing wrong.
Which is the real point for a trader. In a book, liquidity leaving means orders were cancelled by people who chose to. In a pool, liquidity leaving is providers withdrawing capital for reasons that may have nothing to do with a view on price — and it changes what your exit costs.
What to take from it
Ask the question the structure actually answers. Not “what is the price”, but what does the price become at my size. The NoVo Crypto Market Map reads pools on that basis: depth, what it costs to move, and whether that depth is arriving or leaving.