What Are Stablecoins? A Beginner's Guide

A stablecoin is a cryptocurrency designed to hold a fixed value, usually one US dollar per token. Instead of swinging with the market the way Bitcoin or Ethereum can, a stablecoin aims to be worth the same amount today, tomorrow, and next month. That steadiness makes stablecoins the working currency of crypto: traders use them to price coins, park profits, and move money between platforms. This guide explains how they work, the three main designs, and what happens when a peg breaks.

What Is a Stablecoin?

A stablecoin is a crypto token built to keep a steady price. Most are pegged to a national currency, almost always the US dollar, at a target of one token equals one dollar. Where an ordinary cryptocurrency's price floats freely with supply and demand, a stablecoin has a mechanism working in the background that is supposed to pull the market price back to the peg whenever it drifts.

If you are new to the space, it helps to first understand what a cryptocurrency is: a digital asset recorded on a blockchain that you can hold and send without a bank in the middle. A stablecoin is exactly that, with one twist. It moves like crypto but tries to be priced like a dollar. You can send it across the world in minutes, hold it in your own wallet, and trade it around the clock — and if the design works, each unit stays worth about $1 the whole time.

The word "tries" matters. A peg is a target, not a law of nature. Different stablecoins chase that target in very different ways, and the design a coin uses determines how sturdy its $1 price really is. Those designs are the heart of this guide.

Why Stablecoins Exist

Crypto markets run around the clock, and prices can move sharply within a single day. That volatility created a practical problem: how does a trader step out of a risky position without leaving crypto entirely? Cashing out to a bank account can be slow and costly, and it takes money off the rails where it could be redeployed quickly. Traders wanted something that behaved like dollars but lived on a blockchain.

Stablecoins answered that need, and their uses grew from there. They serve as the pricing currency for many trading pairs, so the numbers you see on an exchange are often stablecoin prices. They give traders a parking spot during turbulence: sell a volatile coin into a stablecoin and your balance stops moving with the market while staying ready for the next trade. They move value between platforms quickly, and in some countries people simply hold dollar-pegged tokens as a steadier alternative to a volatile local currency.

In short, stablecoins are the bridge between traditional money and crypto markets, which is why it is worth understanding how they stay stable — and when they do not.

The Three Types of Stablecoins

All stablecoins promise the same thing, a steady price, but they keep that promise in three very different ways. The backing model is the single most important thing to check about any stablecoin, because it determines what has to go wrong before the price breaks.

Fiat-Collateralized Stablecoins

This is the most common design. A company, called the issuer, sells tokens and holds a matching pool of reserves — cash and cash-like assets intended to back every token one for one. Holders who meet the issuer's requirements can redeem tokens for dollars, and that redemption promise is what anchors the price. The two best-known examples are USDT, issued by Tether, and USDC, issued by Circle. The strength of any fiat-backed coin comes down to what actually sits in its reserves and how smoothly redemption works. Those details vary by issuer and change over time, so look to an issuer's own current disclosures rather than secondhand claims.

Crypto-Collateralized Stablecoins

This model backs the token with other cryptocurrencies locked in smart contracts instead of dollars in a bank. DAI is the best-known example. Because crypto collateral is itself volatile, these systems are overcollateralized: users lock up meaningfully more than one dollar's worth of crypto for each dollar of stablecoin they create. If the collateral's value falls too far, the system automatically liquidates positions to keep the backing intact. The appeal is transparency, since the collateral is visible on the blockchain. The trade-off is that a violent crash in the collateral can stress the whole system at once.

Algorithmic Stablecoins

The boldest and most fragile design holds little or no collateral at all. An algorithmic stablecoin relies on code-based supply incentives: rules that expand the token supply when the price rises above the peg and shrink it when the price falls below, often using a second, paired token to absorb the swings. The mechanism works only as long as people believe it will. TerraUSD (UST) collapsed in May 2022 in one of the most widely documented failures in crypto history, showing how quickly an incentive-only peg can unravel once confidence disappears. That episode is why beginners should treat this category with particular caution.

The three types of stablecoins compared by backing, example, and main risk

Type	Backing	Example	Main risk
Fiat-collateralized	Cash and cash-like reserves held by an issuer	USDT, USDC	Trust in the issuer's reserves and redemption
Crypto-collateralized	Excess crypto locked in smart contracts	DAI	Sharp crash in the collateral's value
Algorithmic	Code-based supply incentives, little or no collateral	TerraUSD (UST)	Confidence spiral, as in the May 2022 collapse

How a Peg Actually Holds

A peg is not magic. It is held in place by three interlocking forces: reserves, redemption, and arbitrage.

Reserves are the assets standing behind the token — dollars and equivalents for a fiat-backed coin, locked crypto for a crypto-backed one. Redemption is the promise that a token can be exchanged for one dollar of value with the issuer or protocol. As long as redemption works, nobody has a reason to sell the token for much less than a dollar, because they could redeem it instead.

Arbitrage is the day-to-day enforcer. If a stablecoin trades at $1.01 on an exchange, traders can obtain new tokens at the $1 source and sell them at the higher market price, and that selling pushes the price back down. If it slips to $0.99, traders buy the discounted tokens and redeem them for a full dollar, and that buying pushes the price back up. Repeated at scale, these small trades sand the price back toward the peg all day long.

Notice what every link in that chain depends on: the belief that redemption will actually happen. If people stop believing, the whole loop can run in reverse. A peg, in other words, is engineering plus confidence.

When Pegs Break: Depeg Risk

A depeg is when a stablecoin's market price moves meaningfully away from its target. Two well-documented episodes show the range of what can happen.

The severe case came in May 2022, when TerraUSD (UST), the algorithmic stablecoin mentioned above, lost its peg and collapsed. As the price slipped, holders rushed for the exit, the supply mechanism that was meant to restore the peg amplified the panic instead, and the token never recovered. It remains the clearest demonstration of how fragile an uncollateralized peg can be.

The milder case came in March 2023, when USDC briefly traded below $1 during a U.S. bank failure before recovering its peg. The episode showed that even a fiat-backed coin can wobble when trouble hits the traditional banking system it relies on — and also that a depeg is not automatically fatal, since the price returned. Both events are history, not accusation — simply the record of what "stable" does and does not mean in practice.

One practical warning belongs in this section. Because stablecoins feel safe, they are a favorite lure for platforms promising outsized returns for depositing them. Unusually high yield on a "stable" asset always means risk is hiding somewhere — in lending, in the platform, or in the peg itself. Too-good-to-be-true yield is one of the classic warning signs covered in our guide on how to avoid crypto scams.

How Traders Use Stablecoins

Open almost any exchange and stablecoins are doing quiet work everywhere. Their most visible job is serving as the quote currency in trading pairs such as BTC/USDT or ETH/USDC: when you check a coin's price, you are often looking at its price in a stablecoin. Each of those conversions still carries costs, and our guide to crypto trading fees explains how spreads and trading fees stack up on every hop.

Stablecoins are also the trader's parking brake. Selling a volatile position into a stablecoin locks in its current dollar value without leaving the platform, and the balance stays ready to redeploy the moment an opportunity appears. Measuring a portfolio in stablecoin terms also makes profit and loss easier to read, because the yardstick itself is not moving.

Finally, stablecoins are the connective tissue between venues. They move between platforms faster than a bank transfer usually does, and on decentralized exchanges they anchor a large share of liquidity pools, so many swaps route through a stablecoin along the way. Our comparison of CEX vs DEX covers where each kind of venue fits and why stablecoin liquidity matters on both.

Stablecoins and Taxes

It is easy to assume that swapping into a stablecoin is a non-event for taxes, since the price barely moves. In many jurisdictions, that assumption is wrong. Tax authorities commonly treat trading one cryptocurrency for another as a disposal of the first asset, and that includes trades into a stablecoin. Sell Bitcoin for USDC and you may realize a taxable gain or loss on the Bitcoin at that moment, even though the USDC just sits near a dollar afterward.

Rules, rates, and reporting thresholds differ by country and change over time, so treat this as a flag rather than advice: keep records of every swap, including moves into and out of stablecoins, and check the rules where you live. Our guide to crypto taxes walks through the common concepts, and a qualified professional can confirm how they apply to you.

Practice First, Then Decide

Reading about pegs is one thing; watching how stablecoin pairs behave in a live market is another. The cheapest way to build that experience is with virtual money, through paper trading, before a single real dollar is at risk.

CustomCrypto is a free iOS app built for exactly this. It gives you a virtual balance you can set anywhere from $100 to $1,000,000 (the default is $10,000), tracks 38 cryptocurrencies with real-time prices from CoinGecko, and lets you run up to 3 portfolios side by side to compare approaches. Everything stays on your device: there are no accounts to create, no ads, and no tracking. It is for practice and education only and is not financial advice.

Spend a few weeks placing practice trades at real prices and the ideas in this guide — quote currencies, spreads, stepping out of a position — stop being abstract. You can download the app and start today.

Frequently Asked Questions

Are stablecoins a safe place to park money?

They are steadier than volatile cryptocurrencies, but they are not risk-free. A stablecoin is only as strong as the mechanism holding its peg, and history includes both brief wobbles and total collapses. A stablecoin is also not a bank deposit and does not come with government deposit insurance. Treat 'stable' as a design goal, not a guarantee.

What is the difference between USDT and USDC?

Both are fiat-collateralized stablecoins that target a price of one dollar per token. USDT is issued by Tether, and USDC is issued by Circle. The basic model is the same: the issuer holds reserves and stands behind redemption. Each company manages its own reserves and publishes its own disclosures, which can change over time, so review the latest reports directly if you want the details.

Can a stablecoin lose its peg?

Yes. TerraUSD (UST), an algorithmic stablecoin, collapsed in May 2022 and never recovered. USDC, a fiat-backed stablecoin, briefly traded below $1 in March 2023 during a U.S. bank failure before returning to its peg. Depegs range from short-lived dips to permanent failure, and the backing model is the biggest factor in which way it goes.

Do I pay taxes when I swap into a stablecoin?

In many jurisdictions, yes. Swapping one cryptocurrency for another is commonly treated as a taxable disposal, and that includes trading Bitcoin or Ethereum into a stablecoin. The gain or loss is measured on the asset you sold, not on the stablecoin you received. Rules vary by country, so keep records of every swap and check local guidance or a tax professional.