Arbitrage
Trading the same asset on two venues at the same time to capture a price difference between them.
Because digital-asset markets are fragmented and run continuously, the same asset can trade at different prices on different venues, and arbitrage traders close those gaps by transacting on both sides at once. The same logic ties an automated market maker's quoted price to deeper markets, links a stablecoin's exchange price to its redemption value, and connects futures prices to spot through cash-and-carry trades. Arbitrage requires capital prepositioned on both venues, since transfers take time, and it is not free of risk: withdrawals can be suspended, transactions can fail, fees can exceed the gap, and one leg can execute while the other does not. The activity is a large part of why quoted prices across venues stay close to one another.
In practice
If a token trades higher on one exchange than another, traders transact on both sides until fees and transfer costs make further activity pointless, which narrows the gap.
The common misunderstanding
Arbitrage is not free money; capital is tied up on both venues, transfers can be delayed or halted, and the gap can close before both legs settle.