Why stablecoins exist
Bitcoin can swing 10% in a day. Ethereum regularly moves 5-8%. That volatility is exciting if you're a trader, but it's a nightmare if you just want to park money, pay someone, or move between trades without getting wrecked by price swings.
That's the problem stablecoins solve. They give you a crypto token worth $1 (or close to it) that you can hold, send, and use in DeFi without worrying about volatility. They're crypto's version of cash.
The numbers tell the story. Stablecoins process more transaction volume than Visa and Mastercard combined on some days. USDT alone has a market cap over $130 billion. They've become the most practical use case for blockchain technology, even if they're not the most exciting.
Types of stablecoins
Not all stablecoins work the same way. How they maintain their peg matters a lot, because it determines how safe your money actually is.
Fiat-backed stablecoins
The simplest model. A company holds dollars (or dollar equivalents) in a bank account, and issues one stablecoin for each dollar held. When you want your dollar back, you redeem the token and they send you the dollar. One-to-one backing.
USDC (Circle): The most transparent fiat-backed stablecoin. Circle publishes monthly attestation reports showing their reserves, which are held in regulated US banks and short-term Treasury bills. It temporarily lost its peg during the Silicon Valley Bank collapse in March 2023 (some reserves were held there) but recovered quickly.
USDT (Tether): The largest stablecoin by market cap and trading volume. Tether's reserve transparency has been controversial for years. They've been fined by regulators, they took years to publish proper attestations, and their reserves include not just cash but commercial paper and other assets. Despite all that, USDT has maintained its peg through multiple market crashes. It's the most used stablecoin, especially in Asia and for cross-border payments.
The risk with fiat-backed stablecoins is counterparty risk. You're trusting the issuing company to actually hold the reserves they claim. You're also trusting that their bank won't fail and that regulators won't freeze the assets. It's not custodying your own keys. It's trusting a company.
Crypto-backed stablecoins
Instead of dollars in a bank, these stablecoins are backed by other crypto assets locked in smart contracts. Because crypto is volatile, they're over-collateralized. To mint $100 of stablecoins, you might need to lock up $150 worth of ETH.
DAI (MakerDAO/Sky): The oldest and most battle-tested crypto-backed stablecoin. Users deposit collateral (ETH, WBTC, and other tokens) into Maker Vaults and can borrow DAI against it. If your collateral value drops too low, your position gets liquidated to keep DAI backed. DAI has maintained its peg through multiple bear markets.
The upside of crypto-backed stablecoins is that they're more decentralized. No company can freeze your DAI. The downside is capital inefficiency. You need more than a dollar of collateral to create a dollar of stablecoins, and if the market crashes hard enough, the system can become under-collateralized.
Algorithmic stablecoins
These try to maintain their peg using algorithms and incentives rather than collateral. The idea is that the protocol automatically expands or contracts supply to keep the price at $1.
The most famous (or infamous) was UST/Luna. It worked beautifully until it didn't. In May 2022, UST lost its peg and death-spiraled to zero, wiping out $40 billion in value and taking the entire Luna ecosystem with it. Several other algorithmic stablecoins have also failed.
My honest take: pure algorithmic stablecoins without any collateral backing are a fundamentally flawed idea. They work in normal conditions but break catastrophically in extreme conditions, which is exactly when you need stability most. Some newer designs are partially algorithmic and partially collateralized, which is more promising.
Real-world asset (RWA) backed stablecoins
A newer category. These stablecoins are backed by Treasury bills or other real-world assets, and they pass the yield through to holders. USDY from Ondo Finance and sDAI from MakerDAO are examples. You hold a stablecoin and earn yield from the underlying Treasuries. It's like a money market fund on-chain.
This is probably the most interesting area of stablecoin innovation right now. When short-term Treasury rates are 4-5%, holding a yield-bearing stablecoin beats holding regular USDC at 0%.
What people use stablecoins for
Trading pairs. Most crypto trading happens against stablecoins. When you sell BTC, you're usually selling it for USDT or USDC. Stablecoins let you exit a position without going back to fiat.
DeFi. Stablecoins are the backbone of decentralized finance. Lending, borrowing, yield farming, and liquidity provision all heavily involve stablecoins. The biggest liquidity pools on DEXs are stablecoin pairs.
Cross-border payments. Sending USDC from the US to the Philippines takes minutes and costs cents. Sending dollars through traditional banking takes days and costs $25-50 in fees. For remittances and international payments, stablecoins are genuinely better than the existing system.
Savings in unstable economies. People in countries with high inflation or currency controls use stablecoins to hold dollars when they can't easily access traditional dollar accounts. In Argentina, Turkey, and Nigeria, stablecoins are popular precisely because the local currency is unreliable.
Payroll and business payments. More companies are paying contractors and freelancers in stablecoins, especially for international payments where traditional banking is slow and expensive.
Risks you should know about
"Stable" is relative. Here are the real risks:
De-peg risk. Stablecoins can lose their peg. UST went to zero. USDC temporarily dropped to $0.87. Even USDT has had brief de-peg events. The question isn't whether a stablecoin will ever wobble. It's whether it can recover.
Counterparty risk. For fiat-backed stablecoins, you're trusting the issuer. If Tether lied about their reserves (many people think the full picture is more complicated than they let on), USDT could face a bank run. If Circle's bank partner fails, USDC could temporarily de-peg.
Regulatory risk. Regulators are very interested in stablecoins because they function like money. New laws could force issuers to change how they operate, restrict where stablecoins can be used, or require licensing that smaller issuers can't afford.
Smart contract risk. For crypto-backed and algorithmic stablecoins, bugs in the smart contracts could lead to loss of funds. Even well-audited protocols have been exploited.
Censorship risk. USDC and USDT issuers can (and have) frozen specific addresses. If your address gets blacklisted, your stablecoins become worthless. This is more likely if you interact with sanctioned protocols or addresses, but it's a risk that doesn't exist with decentralized alternatives like DAI.
Which stablecoin should you use?
It depends on what you're doing:
For trading: USDT has the most liquidity on most exchanges. USDC is the safer option but slightly less liquid outside of US platforms.
For DeFi on Ethereum: USDC and DAI are the most widely accepted. Many DeFi protocols prefer USDC for its transparency.
For maximum decentralization: DAI or other crypto-backed stablecoins. No single entity can freeze your tokens.
For earning yield: Look at yield-bearing stablecoins like sDAI or USDY. Or deposit regular stablecoins into lending protocols, but understand the added smart contract risk.
A reasonable approach: diversify across stablecoins the way you'd diversify any portfolio. Don't put everything in one stablecoin. USDC plus DAI covers both the centralized-but-transparent and decentralized-but-complex bases.
The bottom line
Stablecoins are crypto's most practical innovation. They give you the benefits of blockchain (fast, global, programmable) without the volatility. But they're not risk-free. Understand how your stablecoin maintains its peg, who backs it, and what could go wrong.
To understand how stablecoins fit into the broader DeFi ecosystem, read our DeFi guide. For the regulatory side, check the regulation guide. And visit the glossary for definitions of any terms you're unsure about.