A DeFi transaction often begins with a familiar-looking button—Swap, Supply or Borrow—but the click can involve a wallet, several smart contracts, an oracle, a stablecoin issuer and the blockchain that settles the result. Decentralised finance is the collection of applications built from those components.
Users can exchange assets, supply liquidity, borrow, lend or manage collateral without asking a traditional institution to update its private ledger. Control is distributed unevenly, however: development teams, governance voters, hosted interfaces and bridges may remain decisive even when execution occurs onchain.
The components behind a DeFi transaction
A user normally controls an externally owned blockchain account through a wallet. The wallet displays a proposed action and produces a signature. A smart contract applies the protocol’s rules, while the underlying blockchain orders and settles the transaction.
Most users also rely on a web interface to construct the request. The interface is not the protocol: it can be unavailable, compromised or restricted while the contracts remain accessible through another interface or direct transaction. Our dApp guide explains this separation between frontend, infrastructure and onchain logic.
Tokens provide the assets, and oracles may provide external prices. Governance decides parameters and upgrades. Bridges or messaging systems connect separate networks. Each component introduces its own trust and failure assumptions.
What DeFi applications do
Decentralised exchanges let users swap tokens through liquidity pools, request-for-quote systems or onchain order books. An automated market maker calculates prices from pool balances and rules. Traders face fees, price impact, slippage and possible transaction-ordering effects.
Lending protocols allow suppliers to make assets available to borrowers. Open blockchain lending is generally overcollateralised because a contract cannot assess a pseudonymous borrower’s salary or legal credit history. If collateral falls below a threshold, liquidators can repay debt and claim collateral. Aave’s current protocol introduction illustrates this model and its dependence on collateral values and liquidity.
Stablecoins provide a common unit for trading and settlement, but the peg is not a guarantee. Issuer reserves, redemption access, collateral liquidations and smart contracts matter. The stablecoin risk analysis follows those dependencies from reserves to redemption.
Derivatives and structured strategies create leveraged or conditional exposure. Vaults may automate rebalancing or deploy assets across protocols. Automation makes a strategy repeatable; it does not make the return predictable.
Where DeFi yields come from
A displayed annual percentage yield may come from borrower interest, trading fees, token incentives, leverage or a combination. Each source behaves differently. Borrow demand can disappear. Trading fees may not offset adverse price movement. Incentive tokens can fall in value. Leveraged strategies can be liquidated.
Before supplying assets, trace who pays the return and why. If the answer is only “the protocol,” examine token emissions and whether new incentives are subsidising existing users. Our comparison of staking, lending and liquidity provision separates consensus rewards from application-level yield.
DeFi is composable—and failures are composable too
Contracts can call other contracts, allowing developers to combine exchanges, lending pools and collateral in one transaction. This composability is powerful, but it creates hidden dependency chains. A vault can be technically sound and still lose money because an underlying stablecoin depegs, an oracle fails or another protocol pauses withdrawals.
The Financial Stability Board notes that DeFi can inherit and amplify leverage, liquidity mismatch, operational fragility and interconnectedness familiar from traditional finance. Onchain transparency may reveal positions, but transparent code does not ensure that every user can interpret the risk in time.
The main risks
- Contract risk: bugs, unsafe upgrades or unexpected interactions can lock or transfer assets.
- Administrative control: privileged keys may pause markets, change parameters or upgrade code.
- Oracle risk: inaccurate or manipulated prices can create bad debt and wrongful liquidations.
- Liquidity risk: an asset may be difficult to sell or withdraw during stress.
- Bridge risk: moving assets between chains adds contracts, validators or custodians.
- Governance risk: voting power and delegation can be concentrated despite open participation.
- Wallet and approval risk: a malicious signature or unlimited token allowance can expose funds.
- Legal and interface risk: access, disclosures and remedies vary by protocol and jurisdiction.
The Bank for International Settlements describes a “decentralisation illusion”: governance and economic incentives can concentrate control even when execution is distributed. This is a useful question for users, not a verdict that all protocols are identical.
How to evaluate a DeFi protocol
Verify the official contract addresses and the network in use. Read what the protocol actually does, which audits cover the deployed version and whether code is upgradeable. Identify admin keys, multisigs, timelocks, oracle providers, bridge dependencies and emergency controls. Check liquidity and liquidation parameters rather than relying on a headline total-value figure.
For a transaction, inspect the asset, amount, recipient, network fee and permissions displayed by the wallet. Start with an amount small enough to test the complete deposit and withdrawal route. Never sign a message you do not understand, and do not assume a familiar interface proves that the destination contract is genuine.
DeFi’s value lies in programmable settlement and the ability to inspect how applications connect. That same connectivity lets a stablecoin failure, oracle error or governance decision travel through several protocols. The comparison with traditional banking places those dependencies beside the different protections and failure modes of intermediated finance.
Editorial note: this guide was fully reviewed and rewritten on September 3, 2026. It is educational and does not recommend a protocol or strategy.
