What Is a Stablecoin? USDT, USDC, and Why They Matter
If you’ve spent any time in crypto, you’ve used a stablecoin — probably without thinking much about it. You moved funds into USDC while waiting for a better entry. You earned yield denominated in USDT. You parked gains in DAI between trades. Stablecoins are the pipes that everything else runs through.
They’re also, quietly, one of the most important financial innovations in crypto — and one of the least understood. When they work, they’re invisible infrastructure. When they break, they can take billions of dollars down with them in hours. Understanding what you’re actually holding matters.
What a Stablecoin Is
A stablecoin is a cryptocurrency designed to maintain a stable value — almost always pegged 1:1 to the US dollar, though stablecoins pegged to the euro, yen, and other currencies exist.
The “stable” part is the whole point. Normal cryptocurrencies are volatile by design — Bitcoin and Ethereum can move 10-20% in a day. That volatility makes them useful as speculative assets and networks, but it makes them terrible for everyday transactions. You can’t pay rent in Bitcoin if your landlord doesn’t know what a Bitcoin will be worth by the time they try to spend it.
Stablecoins solve this. They give you the programmability and composability of crypto — you can send them anywhere in minutes, use them in DeFi protocols, hold them in a non-custodial wallet — while maintaining the boring reliability of a dollar balance.
The question is: how does something on a volatile blockchain stay worth exactly $1? The answer depends entirely on which stablecoin you’re talking about, because there are fundamentally different mechanisms — and they carry very different risks.
Fiat-Backed Stablecoins: USDT and USDC
The most straightforward approach: a company holds real US dollars (or dollar-equivalent assets like T-bills) in reserve, and issues tokens on a blockchain in the same amount. One dollar in the bank for every token in circulation. You want to redeem? You send your tokens back; the company sends you dollars.
This is how Tether (USDT) and USD Coin (USDC) work — the two largest stablecoins by a wide margin.
Tether (USDT)
USDT is the oldest and largest stablecoin, launched in 2014. It’s the most traded asset in crypto by volume — on most days, USDT trading volume exceeds Bitcoin. It’s deeply embedded in exchange trading, DeFi, and cross-border remittances, particularly in markets where the dollar is hard to access.
Tether’s history is complicated. For years, the company behind it — Tether Limited — faced persistent questions about whether it actually had the reserves it claimed. A 2021 settlement with the New York Attorney General resulted in an $18.5 million fine and a requirement to publish quarterly reserve attestations. Tether has since moved toward more transparent reporting and shifted reserves toward US Treasury bills (which are considered safer than the commercial paper they previously held).
The reserves have been attested to by independent accountants, though Tether does not publish full audits from Big Four firms the way some other stablecoins do. This remains a point of controversy. The pragmatic view: if Tether were going to collapse due to fractional reserves, there have been plenty of stress tests (multiple market crashes, regulatory actions, FUD cycles) where it would have shown cracks. It’s maintained its peg through all of them. The counterargument: “hasn’t broken yet” is not the same as “is sound.”
USD Coin (USDC)
USDC is issued by Circle, a US-regulated financial company, and was originally issued in partnership with Coinbase. It’s widely considered the more regulated, transparent alternative to USDT. Circle publishes monthly attestations from a Big Four accounting firm (Grant Thornton, then Deloitte) and holds reserves primarily in short-duration US Treasuries and cash.
USDC had its own drama moment in March 2023, when Circle disclosed it had $3.3 billion in deposits at Silicon Valley Bank, which was collapsing that weekend. USDC briefly depegged to $0.87 — an extraordinary event for a “stablecoin.” The peg was fully restored within two days after the US government backstopped SVB deposits, but it was a vivid demonstration that “backed by dollars” doesn’t mean “risk-free.” The dollar backing is only as safe as where those dollars are held.
USDC is generally preferred by institutions and protocols that prioritize regulatory compliance and transparency. USDT is preferred by traders who value liquidity and global accessibility.
Crypto-Backed Stablecoins: DAI
What if you want a stablecoin that doesn’t rely on trusting any company to hold dollars in a bank account? Enter crypto-backed stablecoins.
DAI, issued by the MakerDAO protocol, maintains its dollar peg through a system of over-collateralized crypto loans. You want DAI? You deposit crypto (ETH, WBTC, and other approved assets) as collateral into a Maker vault — significantly more than the DAI you’re borrowing, typically 150% or more. If your collateral value falls too far due to market drops, it gets liquidated to maintain the peg.
The key advantage: no company controls DAI. It’s governed by the MakerDAO DAO (and increasingly by a tokenized treasury system), and the collateral is on-chain and verifiable by anyone at any time.
The tradeoff: it’s capital inefficient. You tie up $150 worth of ETH to borrow $100 in DAI. And in extreme market conditions — say, a fast ETH crash — the liquidation mechanisms can be stressed or even fail, as happened briefly during the March 2020 COVID crash.
MakerDAO has evolved substantially, now holding significant real-world assets (government bonds, tokenized credit) as collateral alongside crypto. This has made DAI more capital-efficient and higher-yielding, but also introduced some irony: the most decentralized major stablecoin now has meaningful exposure to traditional financial assets.
Algorithmic Stablecoins: What Went Wrong
No discussion of stablecoins is complete without addressing algorithmic stablecoins — and specifically, the $40 billion catastrophe that was TerraUSD (UST).
Algorithmic stablecoins attempt to maintain their peg not through collateral but through economic mechanisms and game theory. UST, launched by Terraform Labs and its founder Do Kwon, used a mint-and-burn mechanism with LUNA (Terra’s native token) to maintain the $1 peg. If UST traded below $1, you could burn it to mint LUNA at a profit, theoretically pushing UST’s price back up.
In May 2022, large coordinated withdrawals from the Anchor Protocol (which offered 20% APY on UST deposits — a number that, in retrospect, was a flashing warning sign) began a death spiral. UST depegged, LUNA was minted in massive quantities to try to restore the peg, hyperinflation of LUNA destroyed its value, which further undermined UST’s value, which required more LUNA minting. Within days, UST had lost almost all its value and LUNA had gone from $80 to fractions of a cent. Tens of billions in value evaporated.
Do Kwon was arrested in Montenegro in 2023 and faced fraud charges in both South Korea and the United States.
The lesson from Terra/LUNA: stablecoins that rely on reflexive mechanisms — “the peg holds because people believe the peg holds” — can unravel catastrophically under pressure. The Ponzi dynamic of high yields attracting capital that supports the peg until the yields can’t be sustained is a pattern to recognize and avoid.
Smaller algorithmic stablecoin experiments have continued, but the scale and risk profile of something like Terra has not been replicated — hopefully deliberately.
How Stablecoins Are Actually Used
Beyond the abstract, here’s where stablecoins actually show up in practice:
DeFi collateral and liquidity. Stablecoins are a cornerstone of DeFi. Lending protocols like Aave and Compound accept stablecoins as deposits and collateral. DEXes like Curve Finance exist primarily to enable efficient stablecoin-to-stablecoin swaps. Without stablecoins, DeFi would be dramatically less usable.
Trading pairs. On most centralized and decentralized exchanges, stablecoins serve as the quote currency. Rather than trading every asset against BTC (the older convention), most trading now uses USD-denominated stables.
Cross-border remittances. Sending USDT or USDC across borders is often faster and cheaper than traditional wire transfers or remittance services. This use case is significant in countries with limited banking access or volatile local currencies.
Salary and payroll. A growing number of remote workers and freelancers in crypto-adjacent industries receive payment in stablecoins. Companies like Request Finance and Bitwage facilitate stablecoin payroll.
Savings in dollar terms. In countries with high inflation or restricted dollar access (Argentina, Nigeria, Turkey, and others), stablecoins provide access to dollar-denominated savings that would otherwise be difficult to hold. This is probably the most socially significant use case that gets underreported in Western crypto media.
Yield generation. Stablecoins can be deposited into lending protocols to earn yield, typically with lower risk profiles than volatile-asset yield strategies. Rates vary with market conditions — during bull markets, stablecoin yields can reach 10-15%+ on DeFi protocols; in bear markets, they compress toward 3-5%.
Regulatory Landscape
Stablecoin regulation is one of the most active areas of crypto policy globally.
In the US, the GENIUS Act and similar legislation have attempted to establish a federal framework for stablecoin issuance, including reserve requirements, audit standards, and bank charter pathways. As of early 2026, federal stablecoin legislation has passed the Senate but continues to move through the process. In the meantime, state-level regulation (New York’s BitLicense framework, for example) applies to some issuers.
The EU’s MiCA regulation (Markets in Crypto-Assets) came into full effect and applies comprehensive requirements to stablecoin issuers operating in European markets, including reserve standards and operational requirements.
The direction of travel globally is toward more oversight of stablecoin issuers — particularly the largest ones, which at scale start to look like systemically important financial institutions. This is probably net positive for the space’s long-term legitimacy, even if the compliance overhead is real.
Choosing a Stablecoin: Practical Considerations
Not all stablecoins are interchangeable. Here’s what to think about:
For most users: USDC or USDT. Both are liquid, widely accepted, and have maintained their pegs through multiple crises. USDC for regulatory preference and transparency; USDT for maximum liquidity and CEX compatibility.
For DeFi power users: DAI or newer entrants. DAI’s on-chain verifiability is a genuine advantage for trustless DeFi use. Newer decentralized stablecoins (FRAX, LUSD, GHO from Aave) offer different tradeoff profiles worth exploring.
Avoid anything offering dramatically high yields “risk-free.” Terra’s 20% Anchor yield was a warning sign. If a stablecoin mechanism requires paying unsustainably high yields to maintain demand, that’s a structural fragility.
Check which chain you’re on. USDC on Ethereum and USDC on Polygon are technically different token contracts, though Circle has been working toward a native issuance model across multiple chains. Bridged versions of stablecoins carry bridge risk in addition to the underlying stablecoin risk.
For tax treatment of stablecoins and stablecoin swaps, see our crypto tax guide.
Frequently Asked Questions
Is a stablecoin the same as actual dollars? No. A stablecoin is a token that’s pegged to the dollar — it aims to be worth $1 but has different risk properties. Unlike FDIC-insured bank deposits, stablecoin holdings aren’t insured. You’re exposed to the issuer’s reserve quality, smart contract risk, and regulatory risk.
Can stablecoins lose their peg? Yes, and it has happened. USDC depegged briefly during the SVB collapse in March 2023. Smaller stablecoins have broken pegs more severely. The larger and more established the stablecoin, the more resilient it tends to be — but “stable” is a design goal, not a guarantee.
What’s the safest stablecoin? No stablecoin is zero-risk, but USDC is generally considered one of the most transparent and regulated options. USDT has the most liquidity. DAI has the most decentralized collateral backing. Each has different risk profiles.
Do I earn yield just by holding a stablecoin? Not by default. Holding USDC in a wallet earns nothing (unlike a savings account). To earn yield, you need to actively deposit it into a lending protocol, savings product, or other yield-generating mechanism.
Are stablecoins good for sending money internationally? Often yes — especially USDT and USDC on faster, cheaper networks like Solana, Stellar, or Polygon. Fees can be a fraction of wire transfer costs, with settlement in minutes. The practical challenge is on-ramp and off-ramp: converting to and from local currency efficiently.
Will governments ban stablecoins? Unlikely for the major USD-backed ones — the US government has shown more interest in regulating and domesticating them than banning them. Some countries have taken harder stances. China has banned crypto broadly. The EU’s MiCA framework creates compliance burdens but doesn’t prohibit stablecoins that meet requirements. Watch regulatory developments in your jurisdiction.