🏦DeFi explained — finance without banks

What DeFi replaces

A traditional bank does three big things for you: it holds your money, it lets you send or receive payments, and it offers products like loans, savings accounts, and currency exchange. DeFi replicates each of these on a blockchain, mostly on Ethereum and a handful of cheaper networks like Solana, Base, and Arbitrum.

Instead of a bank account, you have a wallet you control. Instead of bank transfers, you sign transactions yourself. Instead of a loan officer, you interact with a smart contract — a program on the blockchain that follows fixed rules. The upside is that you keep custody and can access these services from anywhere with internet. The downside is that there is no support line if you make a mistake.

The main DeFi building blocks

• Decentralized exchanges (DEXs) like Uniswap let you swap one token for another without an account. Liquidity providers deposit pairs of tokens and earn a share of the fees.
• Lending markets such as Aave and Compound let you lend stablecoins for yield, or borrow against crypto you already own without selling it.
• Stablecoins like USDC, USDT, and DAI are tokens pegged to a dollar. They are the main unit of account in DeFi — most yields are quoted in stablecoin terms.
• Yield aggregators and liquid staking turn raw assets into productive ones, e.g. by automatically moving USDC to the highest-paying lending market or by staking ETH while keeping a tradable receipt token.
• Bridges move tokens between networks. They are also the single most common place where DeFi users lose money, because a compromised bridge can drain everyone who used it.

How a DeFi transaction actually works

1. 1
   Connect a wallet

   Most DeFi apps use a browser wallet like MetaMask or Rabby. You click 'Connect', sign a free message to prove you own the address, and the app now sees your balance — but cannot touch it without another signature.

2. 2
   Approve the token

   Before any contract can move a token from your wallet, you grant it a spending allowance. Approve the smallest amount needed; unlimited approvals are convenient but become a liability if the contract is ever compromised.

3. 3
   Sign the action

   Swap, deposit, borrow — each is a transaction you sign in your wallet. You also pay a gas fee in the network's native coin (ETH, SOL, etc.) regardless of whether the transaction succeeds.

4. 4
   Verify on-chain

   Once mined, your transaction has a unique hash. You can view it on a block explorer like Etherscan to confirm what happened. There is no statement in the mail — the chain is the statement.

Where DeFi users actually lose money

The clean failure modes are obvious: a bug in a smart contract, a compromised bridge, or a stablecoin that loses its peg. These get headlines, but they account for a minority of personal losses.

Most beginners lose money to messier causes. They sign a malicious 'approval' on a fake site that looks just like Uniswap. They chase 200% yields on a brand-new token that turns out to be a rug pull. They take a loan against a volatile asset and get liquidated when the price drops. They pay $80 in gas to claim a $10 airdrop. None of these are bugs — they are user mistakes that a bank would normally protect you from.

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