Stablecoins are cryptocurrencies pegged to the dollar, the euro or another asset. The largest, USDT and USDC, are backed by dollars and US Treasuries; others are crypto-collateralized (DAI, USDS) or synthetic (USDe).

In crypto markets they act as cash: pairs are quoted in them, traders park funds in them and money moves between exchanges and countries through them. Growing stablecoin supply usually signals new money entering crypto.