A wall is the strike carrying the largest concentration of dealer gamma. Where dealers are long gamma there, their hedging leans against moves through it. That is the entire claim.
What it is not: a level anyone chose, a price anyone is defending, or a commitment of capital. The dealers hedging there would rather not be involved — they are managing inventory they acquired by making markets.
Three things that follow
It has no intent behind it. Nobody decided this price mattered. It is where customers happened to trade, aggregated.
It weakens as it is tested. Hedging against a move consumes the dealer’s capacity and appetite. A wall tested repeatedly is not reinforcing; it is being worn down.
It has an expiry date. Literally — the open interest behind it belongs to a specific expiry and disappears at 08:00 UTC on that day.
What it is genuinely good for
Locating where volatility is likely to be suppressed, and where it stops being suppressed. Price near a large wall tends to move less; price beyond it has less structure holding it — which is why a break is more informative than a touch, as in the call wall.
In crypto, held more loosely still
The book is small against turnover, so the lean is real and easily outweighed. And on a thin book the wall may be one participant’s block trade rather than accumulated positioning.
Both point the same way: use it to set expectations about behaviour, never as a level to trade against as though someone were standing there. Nobody is.