What 2-of-3 multisig escrow actually means
Old-style escrow puts every deposit in one wallet the market controls. Every exit scam of the last ten years worked because that wallet had one key. Multisig replaces that with three.
The setup
A 2-of-3 multisig deposit sits behind three separate private keys. Any two of them together can spend the coins. The three keys are held by the buyer, the seller and the market. No single party can move the deposit alone.
The normal path
Order completes fine. Buyer and seller both sign, coins go to the seller wallet. The market never touches its own key on a happy-path order. It is only there for arbitration.
The dispute path
Either side opens a dispute. A market moderator reviews evidence and cosigns with whichever party they decide is right. That is the second signature. Two signatures move the coins. The other party's key is not needed.
What the market can and cannot do
The market can cosign a stuck order between two parties who both refuse to move. That is it. It cannot spend the deposit alone. It cannot rotate its own key silently to grab wallets. Every exit scam that killed Empire, Evolution, AlphaBay and the rest of them relied on the market holding the wallet with a single key. Multisig makes that specific attack impossible.
What multisig does not protect against
A dishonest seller shipping a rock instead of the product. Multisig cannot solve that. You still need to file a dispute and hope the moderator sides with you. A biased or bought moderator can cosign with the seller and take your money out of the pool. Multisig limits the market's power over deposits, not its power to be a bad arbiter. So the market's dispute history matters. Read the market pages before you commit funds.
Trade-offs
Multisig transactions carry three signatures instead of one, which raises on-chain fees slightly. On Bitcoin the increase is noticeable. On Monero it is smaller. Some markets pass the fee to the buyer, others absorb it. Setup at checkout takes a few extra clicks and a compatible wallet. Not hard, but not zero.
How to know a market really runs multisig
Look at your deposit address at checkout. A 2-of-3 multisig address on Bitcoin starts with bc1q for native SegWit or 3 for P2SH. On Monero the deposit address will be a multisig subaddress. If your checkout shows a single-signature address (starting with bc1p or 1 on Bitcoin, or a standard subaddress on Monero), the market is using classic escrow, not multisig.