What is DeFi?

DeFi in one sentence

Decentralized Finance (DeFi) is a collection of financial services — the same services you already know from banks and brokerages — rebuilt on public blockchains using smart contracts instead of institutions.

A smart contract is a program that runs on a blockchain. It enforces rules automatically: if you deposit tokens, you earn interest; if your collateral drops below a threshold, your loan gets liquidated. No banker decides. The code executes.

What can you do with DeFi?

DeFi recreates nearly every financial service you find in traditional banking, plus some that did not exist before. Here are the major categories:

For a deeper look at each of these services, see our complete DeFi guide.

DeFi vs. traditional banking

The services are familiar. The infrastructure is completely different.

For a full comparison of crypto and traditional banking, including regulatory differences, see Crypto vs. Traditional Banking.

Advantages of DeFi

DeFi has attracted hundreds of billions of dollars in deposits because it offers things traditional finance does not:

• Open access. Anyone with an internet connection and a wallet can participate. No nationality requirements, no minimum balances, no waiting for account approval.
• Transparency. Every transaction, every interest rate, every line of smart contract code is publicly visible on the blockchain. You can verify everything yourself.
• Composability. DeFi protocols plug into each other like building blocks. You can stake ETH, use the staked token as collateral for a loan, and deposit the borrowed tokens into a vault — all in the same afternoon.
• No gatekeepers. No single entity can deny you service, change the terms unilaterally, or freeze your assets (assuming you control your own wallet).
• Competitive rates. Without the overhead of physical branches, employees, and legacy systems, DeFi protocols can pass more value directly to depositors.
• Always open. DeFi runs 24 hours a day, 7 days a week, 365 days a year. Markets never close.

Disadvantages and risks

DeFi is not a free lunch. The tradeoffs are real:

• Smart contract risk. Code can have bugs. Even audited protocols have been exploited. If a smart contract is hacked, deposited funds can be lost permanently.
• No safety net. There is no FDIC insurance, no customer support hotline, no fraud department. If you send tokens to the wrong address or fall for a phishing attack, there is no one to call.
• Irreversible transactions. Blockchain transactions cannot be reversed. Mistakes are permanent.
• Complexity. Understanding gas fees, token approvals, slippage, impermanent loss, and health factors takes time and effort. The learning curve is steep.
• Scams and fraud. The permissionless nature of DeFi means anyone can deploy a smart contract — including malicious actors. Rug pulls, fake tokens, and phishing sites are common.
• Regulatory uncertainty. DeFi exists in a rapidly evolving regulatory landscape. Rules vary by jurisdiction and change frequently.

For more on managing these risks, read our guide to understanding risk in DeFi and our staying safe guide.

Wallets: your key to DeFi

In traditional finance, your bank account is your identity. In DeFi, your wallet is your account.

A crypto wallet stores the private keys that prove you own your assets. The two most popular wallets are:

• MetaMask — the standard wallet for Ethereum and EVM-compatible chains (Arbitrum, Polygon, Base, Optimism).
• Phantom — the leading wallet for Solana.

When you connect your wallet to a DeFi protocol, you are granting it permission to interact with your tokens. You remain in control — the protocol cannot move tokens without your explicit approval.

To understand how wallets and blockchains work at a deeper level, see Blockchain Basics.

Gas fees: the cost of using the network

Every action on a blockchain — sending tokens, swapping, depositing into a protocol — requires a transaction. Each transaction costs a gas fee, paid to the validators who process it.

Gas fees vary by network. Ethereum mainnet can be expensive (a few dollars to tens of dollars per transaction). Layer 2 networks like Arbitrum, Base, and Optimism reduce fees to pennies. Solana fees are typically fractions of a cent.

Gas is one reason DeFi activity has moved heavily to Layer 2 networks — the same protocols, dramatically lower costs.

Total Value Locked: how big is DeFi?

Total Value Locked (TVL) measures the total dollar value of all crypto deposited across DeFi protocols. It is the most widely used metric for gauging DeFi's size and growth.

At its peak in late 2021, DeFi TVL exceeded $180 billion. It has since fluctuated with market conditions, but the ecosystem continues to grow in the number of protocols, chains, and use cases. For a detailed look at TVL and what it really tells you, see What Is TVL?

The problem DeFi creates

DeFi's openness is its strength — and its biggest user experience problem. A typical DeFi user might have:

• Tokens spread across 3-5 different blockchain networks
• Positions in 8-10 different protocols
• A mix of lending, staking, liquidity, and vault positions
• Dozens of different tokens, some of which are receipt tokens representing positions in other protocols

Keeping track of all this — what you own, what you owe, what you are earning, and what risks you are exposed to — is genuinely difficult. Most people end up with spreadsheets, browser bookmarks to six different dashboards, and a vague sense that they have forgotten something.

Where to go from here