Ethereum is the leading smart contract platform. It allows developers to build decentralised applications (dApps) and enabled the explosion of DeFi, NFTs, and token issuance. Transitioned from Proof of Work to Proof of Stake in 2022.
DeFi refers to a suite of financial services — lending, borrowing, trading, yield generation — built on public blockchains, primarily Ethereum. It aims to replicate and disintermediate traditional finance without banks or intermediaries. At its peak in 2021, over $180 billion was locked in DeFi protocols.
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.