What is Not your keys, not your coins?
The maxim that coins held by a third party are that party's coins and your claim against them.
The phrase is a slogan, but the underlying point is precise: on-chain, control follows the key. A custodial balance is an entry in somebody's database backed by a promise.
Repeated exchange failures have made the point empirically rather than rhetorically. It does not mean custody is always wrong; it means the risk should be a decision, not a surprise.
Related terms
Custodial
An arrangement where a third party holds the keys and you hold a claim against them.
Keys & custodySelf-custody
Holding your own private keys rather than trusting a third party to hold coins for you.
EconomicsCounterparty risk
The risk that the other side of an arrangement fails to deliver — an exchange, a custodian, a lender.
This definition is part of the Bitcoin Logical glossary. For the fuller explanation, start with Learn, or see the live numbers on The Bitcoin Signal.