What Is DeFi? How Decentralized Finance Works and What Can Go Wrong
What Is DeFi? How Decentralized Finance Works and What Can Go Wrong
Most financial services people use every day — savings accounts, loans, currency exchange, trading — involve a central institution. A bank holds your money. A broker executes your trades. A payment processor moves your funds. These institutions are regulated, insured to varying degrees, and accountable to legal frameworks. When something goes wrong, there are established channels for dispute and recovery.
DeFi is a different architecture. The institution is replaced by a protocol — a set of rules encoded in smart contracts on a blockchain. There is no company headquarters. There are no customer service agents. There is no regulator with jurisdiction over the contract itself. The rules are written in code. If the code has a flaw, there is no manager to call.
How DeFi actually works
A smart contract is a program that lives on a blockchain and executes automatically when predefined conditions are met. It does not need a human to process a transaction, approve a loan, or release funds — it does these things on its own, according to the logic written into it.
DeFi protocols are built from these contracts. A lending protocol — like Aave or Compound — uses smart contracts to match borrowers with liquidity, calculate interest rates algorithmically, and liquidate collateral automatically if it falls below a threshold. A decentralized exchange — like Uniswap — uses smart contracts to allow two parties to swap tokens directly, without a centralized order book or a company holding either party's funds.
The key property that makes this possible is that the blockchain provides a shared, trustless ledger. Neither party needs to trust the other — or any institution — because the outcome is determined by the contract code, which anyone can read, and executed by the network, which no single party controls.
What DeFi changes about risk
In traditional finance, risk is distributed across a system of institutions, regulations, and insurance schemes. When a bank fails, deposit insurance may cover losses. When a broker commits fraud, regulators can pursue them. When a payment goes wrong, chargebacks provide recourse. None of these mechanisms exist in DeFi.
When you deposit funds into a DeFi protocol, you are trusting the smart contract code to behave as intended. If the code contains a vulnerability — a logic error, an edge case that was not anticipated, an interaction with another contract that was not foreseen — an attacker can exploit it. The funds move to the attacker's address. The transaction is confirmed on the blockchain. It cannot be reversed.
In 2024 and 2025, DeFi protocols lost billions of dollars to exploits of exactly this kind. Some were sophisticated attacks requiring deep technical knowledge. Others exploited bugs that had been publicly documented in similar contracts for years. In several cases, protocols that had been audited multiple times by reputable security firms were still exploited — because audits check for known vulnerability patterns, not all possible ones.
The risk is not only in the contracts themselves. DeFi protocols interact with each other. A lending protocol may accept a token issued by another protocol as collateral. If that token's protocol is exploited and the token's value collapses, the lending protocol is left with collateral worth less than the debt it secured. This is what happened when the Kelp DAO bridge was exploited in April 2026 — the stolen rsETH was deposited into Aave as collateral, leaving Aave with unbacked debt and triggering a liquidity crisis that froze markets and caused billions in withdrawals across the ecosystem.
The interconnection that makes DeFi composable — the ability to combine protocols like building blocks — is also what makes failures propagate.
What decentralized actually means in practice
The word decentralized is used loosely in crypto, and DeFi is no exception. Many protocols that describe themselves as decentralized retain meaningful centralization in practice.
Admin keys — special permissions that allow a team to pause a protocol, upgrade contracts, or change parameters — are common. If those keys are compromised, the attacker inherits those permissions. If the team decides to use them in ways that harm users, there may be limited recourse. The Wasabi Protocol incident in 2024 illustrated this: admin key access allowed a unilateral decision that disadvantaged users, without any on-chain vote or user consent.
Governance tokens — tokens that grant holders voting rights over protocol decisions — are another mechanism. In theory, they distribute control to the community. In practice, voting participation is often low and token distribution is often concentrated among early investors and the founding team, meaning governance can be captured by a small group.
None of this makes DeFi uniformly dangerous. Some protocols are genuinely well-designed, have been operating without incident for years, and have governance structures that function meaningfully. The point is that decentralized is a description that requires scrutiny, not a guarantee of safety.
Understanding DeFi is not about deciding whether to use it. It is about knowing what you are agreeing to when you do. The absence of a central authority is a feature of the architecture. Its consequences — no recourse, no insurance, no one to call — are features of the same architecture.