以太坊作为智能合约平台的先驱和去中心化金融（DeFi）的摇篮，孕育了丰富多样的DeFi应用，这些应用基于区块链技术，旨在重建传统金融体系，提供开放、透明、无需许可的金融服务，以下将以太坊上DeFi的主要类别和代表性项目进行介绍：

去中心化交易所（DEXs）

DEXs是DeFi生态中最基础也最活跃的组成部分,允许用户直接进行加密货币的兑换，无需依赖传统做市商或中央托管。

1. Uniswap (UNI)： arguably the most famous DEX on Ethereum, it pioneered the automated market maker (AMM) model, particularly the constant product market maker (x * y = k formula). Users can trade any ERC-20 token against ETH or other tokens directly from their wallets.
2. SushiSwap (SUSHI)： originally a fork of Uniswap, SushiSwap introduced additional features like yield farming (staking SUSHI to earn fees) and a yield aggregator (Kashi).
3. Curve Finance (CRV)： focused on providing stablecoin trading with low slippage and fees. It uses an AMM model optimized for assets with low volatility, making it popular for stablecoin swaps and providing liquidity to various stablecoin pools.
4. Balancer (BAL)： operates as both a DEX and a liquidity provider protocol. It allows users to create custom liquidity pools with multiple assets and different weights, rather than just 50/50 pools like Uniswap initially.

借贷协议

借贷协议允许用户抵押加密资产借出其他资产,或出借自己的资产以赚取利息。

1. Aave (AAVE)： one of the leading lending protocols, offering both flash loans (unsecured, instant loans repaid within the same transaction) and traditional lending markets. Users can borrow a variety of assets and earn interest on their deposits.
2. Compound (COMP)： another pioneer in decentralized lending, it introduced the concept of cTokens (e.g., cDAI, cETH), which represent a user's deposited assets and accrue interest over time. COMP tokens are distributed to both lenders and borrowers as governance rewards.
3. MakerDAO (MKR)： best known for generating the stablecoin DAI. Users lock up ETH or other collateral (via Maker Vaults) to generate DAI, which is pegged to the US dollar. MKR holders govern the system and manage stability fees.
4. Compound V3 (updated version)： has introduced more capital-efficient lending with concentrated liquidity and other optimizations.

稳定币

稳定币是DeFi生态的重要基础设施,旨在与法定货币（如美元）保持稳定价值，用于交易、储值和作为借贷抵押品。

1. DAI (DAI)： a decentralized, collateral-backed stablecoin issued by MakerDAO. Its value is maintained through over-collateralization and algorithmic adjustments.
2. USDC (USDC)： a regulated, fiat-collateralized stablecoin issued by Circle and Coinbase, backed by US dollars and short-term US government bonds. It is widely used across DeFi protocols for its stability and regulatory compliance.
3. USDT (USDT)： another major fiat-collateralized stablecoin, issued by Tether. It is one of the most traded cryptocurrencies and provides liquidity to various DeFi platforms.

衍生品协议

衍生品协议允许用户对资产价格进行投机、对冲风险或获得杠杆 exposure。

1. Synthetix (SNX)： allows users to mint and trade "Synths" - synthetic assets that track the price of real-world assets like stocks, commodities, cryptocurrencies, and fiat currencies (e.g., sETH, sBTC, sUSD).
2. Perpetual Protocol (PERP)： a decentralized platform for trading perpetual contracts (futures with no expiry date) with high leverage. It uses an AMM model and funding rates to keep the contract price close to the underlying asset's spot price.
3. Opyn (formerly)： focused on decentralized options trading, allowing users to buy and sell options on Ethereum and other assets.

资产管理/收益聚合器

这类协议帮助用户优化其加密资产的收益率,自动将资金分配到各种高收益的DeFi协议中。

1. Yearn Finance (YFI)： one of the earliest and most well-known yield aggregators. It automatically moves user funds between different lending protocols (like Aave, Compound) to maximize returns.
2. Convex Finance (CVX)： focuses on optimizing yield for liquidity providers (LPs) on Curve Finance and other protocols. It offers boosted rewards for staking CRV and other tokens.
3. Balancer (BAL)： as mentioned earlier, also functions as a yield aggregator through its various pools.

结构化产品与保险

1. Set Protocol (SET)： allows users to create and manage tokenized baskets of assets, known as "Sets," which can track specific investment strategies or indices.
2. Nexus Mutual (NXM)： a decentralized insurance platform where users can purchase coverage against smart contract risks, exchange rate risks, and other DeFi-related perils. It is governed by NXM token holders.

其他重要DeFi领域

• 预言机：如 Chainlink (LINK)，为DeFi协议提供安全可靠的外部数据（如价格、事件触发），是许多DeFi应用（尤其是借贷和衍生品）正常运行的关键基础设施。
• 钱包与身份：如 MetaMask, Argent，是用户与以太坊DeFi交互的入口，管理私钥和数字身份。
• 跨链桥：如 Multichain (原Anyswap), Hop Protocol，允许资产在不同区块链（如以太坊与BSC、Polygon等）之间转移，拓展了DeFi的资产互通性。

以太坊的DeFi生态系统极其庞大且不断创新,上述类别和项目只是其中的冰山一角，从交易、借贷、稳定币到衍生品和资产管理，DeFi正在逐步构建一个完整的金融平行世界，用户在参与以太坊DeFi时也需注意智能合约风险、市场波动风险以及监管不确定性等因素，随着技术的不断发展和用户体验的持续优化，以太坊DeFi有望继续引领全球去中心化金融的浪潮。