Stablecoins are cryptocurrencies designed to maintain a stable value, typically pegged to the US dollar. They exist in three main types: fiat-backed (USDT, USDC), crypto-backed (DAI), and algorithmic — the latter having a catastrophic track record including the $40B Terra collapse.
Tether (USDT) is the world's largest stablecoin by market capitalisation and trading volume. It is issued by Tether Limited and claims to be fully backed by US dollar reserves. USDT is the primary trading pair on most cryptocurrency exchanges globally.
Terra was an algorithmic stablecoin protocol that spectacularly collapsed in May 2022, wiping out approximately $40 billion in value within days. Its UST stablecoin lost its peg and LUNA became worthless, triggering contagion across the entire crypto market.