What is a stablecoin?
A stablecoin is a cryptocurrency designed to hold a fixed value, almost always pegged to the US dollar. One token is meant to be worth one dollar today, tomorrow, and six months from now. If you have wondered what is a stablecoin and why it matters, the answer starts with volatility.
Bitcoin can move thirty percent in a month. That makes it almost useless as everyday money. A stablecoin solves this by combining the speed and openness of crypto with the price stability of ordinary currency.
Understanding what is a stablecoin matters even if you have no interest in trading. These tokens now settle enormous amounts of crypto activity. They appear in wallets, on exchanges, and increasingly in regulated payment systems. If you use crypto at all, you will encounter one.
What is a stablecoin trying to solve?
Cryptocurrency was designed to be digital money. Volatility made that almost impossible in practice. You cannot pay a supplier in something that might drop twenty percent before the invoice clears.
A stablecoin answers this problem directly. It uses a blockchain to move value quickly and openly. A blockchain is a shared digital ledger that records transactions without a central authority. In almost all cases, the stablecoin’s price is anchored to the US dollar.
The mechanics of how a stablecoin holds its peg differ significantly between types. There are three main approaches, each carrying very different levels of risk.
Most people holding stablecoins have never checked which type they have. That is worth changing.
How fiat-backed stablecoins work
Fiat-backed stablecoins are the most common type. The model is simple. For every token in circulation, the issuer holds real dollars in a bank account or in short-dated government bonds.
You buy a token, they hold your dollar. You redeem it, they return the dollar.
Most people first asking what is a stablecoin are really asking about fiat-backed ones. USDC, issued by Circle, is the leading example. It publishes monthly attestations confirming its reserves. Tether (USDT) operates on the same principle but has faced long-running questions about exactly what backs its holdings.
On an exchange screen, USDC and USDT look almost identical. The risk underneath them can differ significantly. Knowing which stablecoin you hold, and what backs it, is basic due diligence. For a full account of Tether’s history, our post on what is USDT and why Tether is controversial covers the full story.
Crypto-backed and algorithmic stablecoins
Crypto-backed stablecoins hold other cryptocurrencies as collateral (assets pledged as security) rather than dollars in a bank. You lock up more collateral than the value of stablecoins you borrow. For instance, you might deposit £150 of Ether into a smart contract to receive £100 in stablecoins.
A smart contract is a self-executing piece of code that runs automatically on a blockchain. It holds your collateral and issues tokens without needing a company to manage the process. DAI, from MakerDAO, is the best-known crypto-backed stablecoin.
The advantage is that it runs on code. No single company controls it. The risk is that a fast crash in the collateral can overwhelm the buffer. Over-collateralisation protects against gradual falls, not sudden ones.
Algorithmic stablecoins try to hold their peg through supply mechanisms, with no reserves at all. When demand rises, the system creates new tokens. When demand falls, it contracts supply. The logic sounds clean in a whitepaper.
In practice, it has failed badly. TerraUSD held its dollar peg through a sister token called Luna. In May 2022, confidence in that relationship broke down.
The peg snapped. Around 40 billion dollars of value was wiped out within days.
Anyone holding TerraUSD lost almost everything. Algorithmic stablecoins are the highest-risk category by a wide margin. They should be approached with significant caution, if at all.
How stablecoins are actually used
Most people first encounter stablecoins on a crypto exchange. When you buy Bitcoin on Kraken or Coinbase, the price displays in dollars. The settlement unit is often a stablecoin, not a bank wire. No conversion to pounds is needed between trades.
Beyond trading, stablecoins are used for cross-border payments. A UK business paying a supplier abroad can send USDC and have it arrive in seconds. There is no SWIFT delay. There are no correspondent bank fees.
For people in countries with weak or unstable currencies, a dollar-pegged stablecoin can also serve as a practical store of value.
In the UK, USDC is the stablecoin most British users are likely to hold. It is accepted across most regulated exchanges serving UK customers. Holding USDC is not the same as holding dollars in a bank. It is not protected by the Financial Services Compensation Scheme (FSCS).
Some platforms offer high interest rates on stablecoin deposits. Those yields are not free money. They come from lending, liquidity provision, or smart contract risk.
If the yield seems too high, something is taking on risk to generate it. Find out what before committing funds.
Stablecoin regulation in the UK
UK stablecoin rules are tightening. The Financial Conduct Authority (FCA) and the Bank of England have signalled that stablecoins used for payments will come under formal regulation. Issuers will need to hold safe, transparent reserves.
Holders will gain the legal right to redeem stablecoins at face value, known as “at par”. That is a meaningful protection that most holders currently lack. The direction of travel is toward making regulated stablecoins look more like e-money.
Some issuers operating in the UK will not meet the new standards. They will exit the market. That reduces risk for the people who remain. Fewer, better-regulated stablecoins is a better outcome than a wide range of uneven-quality ones.
For a broader picture of the UK’s crypto regulatory framework, our guide to how crypto is regulated in the UK sets out the full picture. The FCA also maintains a dedicated cryptoassets page that is updated as rules are confirmed.
What to check before you hold a stablecoin
Knowing what is a stablecoin is the starting point. Knowing which type you hold is the next step. Fiat-backed stablecoins from regulated issuers carry much lower risk than crypto-backed or algorithmic alternatives. For most UK users, USDC is the practical choice.
Check who issued it and what backs it. If the issuer does not publish regular reserve attestations, that is a warning sign. What is a stablecoin’s reserve model if not publicly documented? It is a promise without a paper trail, and that has gone wrong before.
Be careful with yield. Any platform offering high returns on stablecoin deposits is taking risk somewhere to generate it.
Sometimes that risk is clearly disclosed. Often it is not. If you cannot identify where the yield comes from, that is reason enough to pause.
The fundamental point about what is a stablecoin applies to all three types: its stability depends on the mechanism that keeps it pegged. Fiat backing can fail if reserves are fraudulent. Crypto backing can fail in a fast crash.
Algorithmic pegs can fail almost instantly. Choosing a well-backed, regulated stablecoin from a credible issuer is the only protection that holds up over time. That is the practical answer to what is a stablecoin worth holding.
This article is for informational purposes only and does not constitute financial advice. Cryptocurrency investments carry significant risk. Always do your own research before making any financial decisions.