What is DeFi? Decentralized finance explained, with its real risks

DeFi, short for decentralized finance, is a set of financial apps that run on public blockchains, letting you trade, lend and borrow directly from your own wallet without a bank or broker in the middle. It is open to anyone with an internet connection, and that openness brings real risks you need to understand first.

How DeFi works

Traditional finance relies on companies to hold your money and keep the records. DeFi swaps those companies for smart contracts: programs deployed on a blockchain such as Ethereum that hold funds and follow fixed rules anyone can inspect. As ethereum.org puts it, the goal is an open alternative that does not require permission to use.

In practice you connect a self-custody wallet to an app's website, review what the app wants to do, and sign a transaction. No account sign-up or identity check is usually involved, and no one can freeze your account. The flip side is that no one can reset your password or refund a mistake either.

You can browse the main projects in our DeFi category.

Decentralized exchanges and AMMs

A decentralized exchange (DEX) lets you swap one token for another straight from your wallet. Many DEXs do not use a traditional order book with buyers and sellers placing bids. Instead they use an automated market maker (AMM).

An AMM holds two tokens in a pool and sets the price with a formula based on how much of each is in the pool. When you buy one token, you add the other, and the price shifts. Larger trades in smaller pools move the price more, an effect called slippage. Wallets and DEXs let you set a maximum slippage so a trade fails rather than fill at a far worse price.

Lending and borrowing markets

DeFi lending protocols pool deposits from lenders and let others borrow from that pool. Lenders earn interest; borrowers pay it. Because there are no credit checks, loans are usually overcollateralized: you must deposit more value than you borrow.

If your collateral falls in value, your position can be liquidated. Aave, one of the largest lending protocols, tracks this with a “health factor”; once it drops below 1, others can repay part of your debt and claim some of your collateral plus a bonus. Liquidations happen automatically, at any hour, with no margin call phone call. Our liquidation calculator and lending and borrowing hub explain the math.

Prices inside these protocols come from oracles, services that feed outside data onto the blockchain. A faulty or manipulated oracle is a well-known cause of DeFi losses.

DeFi compared with a centralized exchange

Many people meet DeFi after using an app like a centralized exchange. The two can look similar on screen, but who is responsible for what is very different.

Neither model is risk-free. DeFi removes the need to trust a company with custody, but it shifts nearly all of the responsibility onto you and onto the quality of the code. The SEC's custody bulletin makes the same basic point about self-custody: if your keys are lost or stolen, there is usually no one to call.

Stablecoins in DeFi

Stablecoins, tokens designed to track a currency like the US dollar, are the everyday money of DeFi. People trade against them, lend them for interest, and borrow them against other crypto. That makes the quality of the stablecoin a risk in its own right: if a stablecoin loses its peg, every pool and loan built on it feels the shock. Our stablecoins hub compares how the major ones are backed.

Liquidity pools and impermanent loss

The tokens inside AMM pools come from users called liquidity providers. They deposit a pair of tokens and earn a share of the trading fees.

The catch is impermanent loss. When the prices of the two tokens move apart, the pool automatically rebalances, leaving you with more of the token that fell and less of the one that rose. Uniswap's documentation walks through why a provider's position can end up worth less than if they had just held the tokens. The loss is called “impermanent” because it shrinks if prices return to where they started, but it becomes permanent when you withdraw at a different ratio.

Yields and where they come from

DeFi apps often advertise yields as an APY. Before you chase one, ask where the money comes from. Legitimate yield usually has one of four sources:

• Borrower interest paid into a lending pool.
• Trading fees earned by liquidity providers.
• Staking rewards from securing a network, covered in our staking guide.
• Token incentives, where a protocol pays you in its own token to attract deposits. These can shrink quickly and are only worth what that token is worth.

Wallet approvals: the risk you sign yourself

To let a smart contract move a token for you, your wallet signs a token approval. Many apps request unlimited approvals by default for convenience. That permission stays active until you revoke it, so if the contract is later exploited, or if you approved a malicious one, your tokens can be drained without any further signature.

• Read what each signature request actually allows before confirming.
• Approve only the amount you plan to use when your wallet allows it.
• Review and revoke old approvals periodically using a reputable approval checker.
• Never sign anything on a site you reached through an ad, a direct message or a “claim your airdrop” link.

Our guide to phishing and wallet drainers shows how fake sites abuse approvals and signatures.

Smart-contract risk and hacks

Code can have bugs, and in DeFi a bug can mean an immediate, irreversible loss. Audits reduce the risk but do not eliminate it. Other weak points include admin keys that can upgrade contracts, oracle manipulation, and bridges between chains.

Recent data offers a mixed picture. Chainalysis counted more than $3.4 billion stolen across the crypto industry from January to early December 2025, with the February Bybit exchange breach alone accounting for about $1.5 billion. The same research found that DeFi hack losses stayed relatively low in 2024 and 2025 even as deposits recovered, which it linked to better monitoring and faster incident response. Lower is not zero, and individual protocols still fail.

How to try DeFi with small amounts

1. Use a separate wallet for experiments, holding only what you are prepared to lose. Keep long-term savings elsewhere.
2. Start on a layer 2 network, where fees are often low enough to make small tests sensible.
3. Stick to well-established protocols with long track records, public audits and clear documentation, and bookmark their official sites.
4. Make one simple move first, such as a small stablecoin swap, then check it on a block explorer.
5. Revoke approvals when you are done, and write down what each step cost in fees so you understand the real economics before scaling up.
6. Keep records of every transaction for taxes; see our tax guide.

Where to go next

This lesson follows how to buy crypto safely and how to send crypto safely. Next, learn how staking works, then see how layer 2 networks make DeFi cheaper, and finish with stablecoins.

Updated October 4, 2026 by The Crypto Guide editorial team. Educational content, not financial, legal or tax advice. Spot an error? Request a correction.