What is DeFi? Decentralized Finance Explained

In this tutorial, you'll learn about What is DeFi? Decentralized Finance Explained. We cover key concepts, practical examples, and best practices to help you understand and apply this topic effectively.

What You'll Learn

Understand the core DeFi primitives — DEXes, lending markets, AMMs, liquidity pools, yield farming, and how they create an open financial system.

Why It Matters

DeFi is the largest category of Blockchain applications with billions in value. It offers financial services without banks, brokers, or intermediaries.

Real-World Use

Swap tokens without creating an account, earn interest on crypto deposits, borrow against your holdings, or provide liquidity and earn fees.

What is DeFi?

DeFi (Decentralized Finance) is a system of financial applications built on Blockchain that operates without intermediaries. Anyone with an internet connection can participate.

Traditional Finance            DeFi
┌────────────────────┐       ┌────────────────────┐
│ Bank              │       │ Smart contracts    │
│  ↓                │       │  ↓                 │
│ Broker            │       │ Protocol governed  │
│  ↓                │       │   by code          │
│ Clearing house    │       │  ↓                 │
│  ↓                │       │ Permissionless     │
│ Central bank      │       │   access           │
└────────────────────┘       └────────────────────┘

Key DeFi Primitives

Decentralized Exchanges (DEXes)

DEXes like Uniswap let you trade tokens without a central order book. They use Automated Market Makers (AMMs):

// Simplified AMM formula (constant product)
// x × y = k
// Where x = ETH reserves, y = Token reserves, k = constant

function swap(uint256 ethIn) public returns (uint256 tokenOut) {
    uint256 k = ethReserve * tokenReserve;
    uint256 newEthReserve = ethReserve + ethIn;
    uint256 newTokenReserve = k / newEthReserve;
    tokenOut = tokenReserve - newTokenReserve;
    // Send tokens to user
}

Lending Protocols

Aave and Compound let you lend crypto for interest or borrow against collateral:

Lender deposits ETH → Earns interest (variable rate)
Borrower deposits 150% collateral → Borrows USDC
If collateral drops below threshold → Liquidated

Liquidity Pools

Instead of matching buyers and sellers, AMMs use liquidity pools — reserves of two tokens:

Liquidity Provider
  ↓
Deposits ETH + USDC into pool
  ↓
Earns 0.3% of every trade
  ↓
Can withdraw share + fees anytime

Yield Farming

Yield farmers move assets between protocols seeking the best returns:

1. Deposit ETH into Aave → get aETH
2. Use aETH as collateral → borrow USDC
3. Add USDC + ETH to Uniswap pool → earn fees
4. Stake LP tokens → earn extra GOVERN tokens
5. Repeat (this is called "yield farming")

Notable DeFi Protocols

Risks