DeFi Explained: Vocabulary and Mechanisms

The short answer

DeFi replaces the intermediary with a smart contract. Instead of an exchange matching your order or a bank holding your deposit, a program holds the assets and follows fixed rules. That removes the company's discretion — and removes the company's ability to reverse a mistake, freeze a theft or refund an exploit.

There is no customer support, no chargeback and no deposit insurance behind a smart contract. Everything below should be read with that in mind.

Foundations

• Smart contract — a program deployed to a blockchain that runs exactly as written when called. It holds assets and enforces rules; it cannot be persuaded, and bugs in it are exploitable by anyone who finds them.
• Protocol — the set of contracts making up one application. A front-end website is only an interface to it, which is why a cloned website can point at a different contract entirely.
• Permissionless — anyone can interact without approval or an account. It also means anyone can deploy something that looks identical to a legitimate protocol.
• Composability — protocols can call each other, so one failure can cascade into applications the user never interacted with directly.
• Total value locked (TVL) — the value of assets deposited in a protocol at a point in time. It measures size, not safety, and it changes constantly; we do not publish TVL figures because we have no licensed live data source for them.

Trading: DEX, AMM, pools and pricing

• Decentralised exchange (DEX) — a protocol that lets wallets trade tokens directly, without depositing them with a company.
• Automated market maker (AMM) — the common DEX design. Instead of matching buyers to sellers, a contract holds two or more assets and prices trades with a formula based on the ratio between them.
• Liquidity pool — the pot of assets an AMM trades against, supplied by users.
• Liquidity provider (LP) — someone who deposits assets into a pool and receives a share of the trading fees, usually represented by an LP token that acts as a claim on the pool.
• Swap — exchanging one token for another through the pool.
• Slippage — the difference between the price you were quoted and the price you received, caused by price movement between submitting and executing.
• Slippage tolerance — the maximum difference you will accept before the transaction reverts. Setting it very high is a common way people lose value on a trade.
• Price impact — how much your own trade moves the pool's price. Large trades against small pools move the price against the trader, which is separate from slippage.
• Impermanent loss — the gap between holding two assets and depositing them into a pool, which appears when their relative price changes. It becomes permanent the moment you withdraw at those prices, and fees earned may or may not offset it.

Lending, collateral and liquidation

• Lending protocol — a contract where depositors supply assets and borrowers take them out against collateral. Rates are usually set by how much of the pool is currently borrowed.
• Collateral — assets you lock so you can borrow. DeFi loans are typically overcollateralised: you post more value than you borrow, because the contract cannot pursue you personally.
• Loan-to-value / health factor — the measure of how close your position is to the protocol's limit. Interfaces name it differently; the concept is the same.
• Liquidation — when collateral value falls past the threshold, the contract sells collateral to repay the loan, usually with a penalty. It is automatic, it does not wait for you, and it can happen during volatility while you are asleep.
• Borrowing to buy more of the same asset amplifies both directions. A falling price reduces the collateral and raises the liquidation risk at exactly the same moment.

Supporting pieces

• Oracle — the mechanism feeding external data, usually prices, to a contract. Contracts cannot see outside their own chain, so a manipulated or stale oracle is a recurring cause of losses.
• Governance token — a token granting votes over a protocol's parameters. Holding one is not ownership of the protocol's revenue and carries no legal claim by default.
• Wrapped token — a token on one chain that represents an asset from elsewhere, backed by the original being held or locked. Its value depends entirely on the arrangement backing it.
• Yield farming — moving assets between protocols to collect fees and token incentives. Returns are variable, often paid in a protocol's own token, and stack every risk of every protocol involved.
• Bridge — infrastructure moving value between chains. It has its own failure modes, covered in the dedicated bridge guide.

Staking a network versus DeFi yield

These are frequently blurred and are not the same thing. Staking secures a proof-of-stake network: the reward comes from the protocol's own issuance and fees, and the main risks are lock-ups, penalties and whoever you delegate through. DeFi yield comes from other users — traders paying fees, borrowers paying interest — or from token incentives, and the main risks are smart-contract failure, liquidation, oracle manipulation and the value of the incentive token itself.

A high advertised return is a description of risk, not a reward for being early. We publish no yield figures or comparisons.

What to check before interacting

1. Reach the interface through your own bookmark and verify the exact domain character by character.
2. Confirm the contract address against the project's own official documentation rather than a search result or a message.
3. Read the wallet prompt: is it a transfer, a spend approval, or a signature? Reject anything you cannot state in one sentence.
4. Prefer a limited approval amount over an unlimited allowance, and revoke permissions you no longer use.
5. Use a separate wallet holding only what you are willing to lose for any protocol interaction.
6. Assume that anything deposited can be lost entirely to a contract bug, regardless of how established the protocol appears.

Common mistakes

• Treating a front-end website as the protocol, so a cloned site feels familiar and safe.
• Approving an unlimited allowance because the interface offered it as the default.
• Judging safety by size or age instead of by what happens if the contract fails.
• Providing liquidity without understanding impermanent loss, then attributing the shortfall to fees.
• Borrowing against a volatile asset without a plan for a fast drawdown.
• Assuming a wrapped asset is the same thing as the asset it represents.

Sources

• Ethereum.org: decentralised finance (DeFi)
• Ethereum.org: smart contracts
• Ethereum.org: oracles
• Investor.gov: crypto asset investor alerts and bulletins