What is cryptocurrency?
Cryptocurrency, usually shortened to crypto, is digital money that exists only as data. Instead of a bank keeping the account book, thousands of computers keep copies of a shared record called a Blockchain. Cryptography, a branch of mathematics for protecting information, secures that record and proves who owns what.
Most cryptocurrencies are not issued by a government or a central bank. Their rules are written in open software, and the network follows those rules. This is why crypto is often called decentralized, although how decentralized a given project really is can vary a lot.
Bitcoin was the first. Its creator, who used the pseudonym Satoshi Nakamoto, published the paper "Bitcoin: A Peer-to-Peer Electronic Cash System" on 31 October 2008. The first block of the Bitcoin chain was mined on 3 January 2009. Since then, thousands of other cryptocurrencies have appeared.
The word comes from cryptography. People also use "crypto" as shorthand for the wider industry of exchanges, apps and projects built around these assets. Digital files are easy to copy, so a system needs a way to stop the same coin being spent twice. This is called the double-spending problem, and blockchains solve it by having the network agree on a single history of transactions.
Crypto is a digital asset whose ownership is recorded on a shared ledger and protected by cryptography. It is not a bank balance, and in most countries it is not a government-issued currency.
How crypto works (blockchain, wallets, keys)
The blockchain: a shared ledger
A blockchain groups transactions into blocks, and each block is linked to the one before it. Changing an old block would break every later link, so past records are very hard to alter. Computers on the network, called nodes, check new transactions against the rules before accepting them.
The network also needs a way to agree on which transactions are valid. Bitcoin uses proof of work, where miners spend computing power to add blocks. Ethereum moved to proof of stake in 2022, where validators lock up coins as a guarantee of honest behaviour.
Users usually pay a small network fee for each transaction. The fee goes to the miners or validators who process it, and it tends to rise when the network is busy.
Wallets and keys
A wallet does not hold coins the way a purse holds cash. It holds keys that let you sign transactions on the blockchain. A public address works like an account number you can share. A private key proves control and must stay secret, and it is usually backed up as a list of words called a seed phrase.
A Crypto Wallet can be an app on a phone or computer, a small hardware device, or an account at a company that holds the keys for you. Each option trades convenience against control and security.
What happens in a transaction
- You create a transfer to the recipient's address and sign it with your private key.
- The transaction is broadcast to the network.
- Nodes check the signature and confirm the funds are available.
- Miners or validators include the transaction in a new block.
- As more blocks are added on top, the transfer becomes harder and harder to reverse.
Blockchain transactions are generally irreversible. If you lose your private key or seed phrase, or send funds to the wrong address, there is usually no help desk that can recover them.
Main types (Bitcoin, altcoins, stablecoins, tokens)
Thousands of crypto assets exist, but most fit into a few broad groups. The table gives a quick map, and the labels overlap in everyday use.
| Type | What it is | Example |
|---|---|---|
| Bitcoin | The first cryptocurrency, with a design limit of 21 million coins | Bitcoin (BTC) |
| Altcoins | Any cryptocurrency other than Bitcoin | Ether (ETH), Solana (SOL) |
| Stablecoins | Crypto designed to track a currency such as the US dollar | USDT, USDC |
| Tokens | Assets issued on top of an existing blockchain | Tokens on Ethereum |
An Altcoin is simply an alternative to Bitcoin. Some aim to improve on Bitcoin's design, and others serve different purposes, such as running applications. A Stablecoin tries to hold a steady value by being backed by reserves or managed by rules, so its stability depends on the issuer and the design.
Some people use "coin" and "token" as if they mean the same thing. A coin usually runs on its own blockchain, while a token is built on another one, and the page on Coin vs Token explains the difference. Projects are often ranked by Market Cap, which is price multiplied by circulating supply. It is a rough size measure and says nothing about quality or safety.
Be careful with newer or obscure tokens. Some are created as jokes or to ride a wave of hype, and they can lose most of their value quickly. A project's name or popularity tells you very little about whether it is sound.
How people use crypto (payments, investing, DeFi)
Payments and transfers
Crypto can move value between people anywhere in the world without a bank in the middle. Some merchants accept it, and some people use it to send money abroad. Fees, speed and acceptance depend on the network and the country.
In Türkiye, a Central Bank regulation that took effect on 30 April 2021 bars the use of crypto assets in payments. Rules differ by country and change over time, so check the current position where you live.
Investing and trading
Many people buy crypto hoping its price will rise, and others trade it actively. Prices can move sharply in short periods, and there is no guarantee of any outcome. Nothing here is investment advice.
Most beginners reach crypto through a centralized exchange, a company that matches buyers and sellers and often holds assets on their behalf. Others use decentralized exchanges, which run on smart contracts and connect to the user's own wallet. The two models carry different risks, and neither removes price risk.
DeFi and other uses
Decentralized finance, or DeFi, offers services such as swapping and lending through smart contracts. A smart contract is a program stored on a blockchain that runs automatically when its conditions are met. Other uses include NFTs, which are unique digital items, and tokens that give holders a say in how a project is run.
- Payments and remittances.
- Holding or trading as an asset.
- DeFi services such as swaps and lending.
- NFTs and other digital collectibles.
- Governance voting in some projects.
Benefits and risks
Possible benefits
- Open access: anyone with an internet connection can usually create a wallet.
- Transfers can reach another country in minutes at a cost that is sometimes low.
- Ownership can be self-held, without a company holding your assets.
- Public blockchains can be inspected by anyone, which supports transparency.
- Programmable features, such as smart contracts, allow new kinds of services.
Main risks
- Price volatility: values can rise and fall sharply, and you can lose everything you put in.
- Scams and fraud: fake giveaways, impersonation, fake platforms and "guaranteed return" schemes are common.
- Hacks and platform failure: exchanges, apps and smart contracts have been attacked or have collapsed.
- Loss of access: lost keys or seed phrases usually mean lost funds.
- Limited protection: a bank-style deposit guarantee usually does not apply.
- Regulatory change: rules on trading, taxes and payments can shift quickly.
Only use money you can afford to lose, and never share your seed phrase or private key with anyone. Anyone promising guaranteed or risk-free returns from crypto should be treated with suspicion.
Crypto vs fiat money
Fiat Currency is government-issued money, such as the Turkish lira or the US dollar, that is backed by the authority of the state rather than by a physical commodity. Cryptocurrency differs in who issues it, how its supply is set and how it is overseen.
| Feature | Cryptocurrency | Fiat money |
|---|---|---|
| Issuer | Usually software rules, no single issuer | Government and central bank |
| Form | Digital only | Cash and digital bank balances |
| Supply | Set by code, often capped or predictable | Set by monetary authorities |
| Legal tender | Generally not, in most countries | Yes, within its own country |
| Price stability | Often volatile | Relatively stable, though inflation applies |
| Reversing a payment | Usually impossible | Often possible via banks or card disputes |
| Oversight | Varies and still developing | Established banking regulation |
Fiat money is also not free of problems, since inflation reduces what a unit of currency can buy over time. Some people look to crypto with a fixed supply for that reason, but a fixed supply does not protect against falling prices. Crypto is better seen as a different kind of asset than as a replacement for everyday money. Many people hold both, and the two systems increasingly connect through exchanges and stablecoins.
How to get started safely (links to guides)
Learning first is the safest step. The points below describe general good practice, not advice to buy or sell anything.
- Learn the basics: understand blockchains, wallets, keys and how transactions work before moving any money.
- Check your local rules: legal status and tax treatment differ by country.
- Research any platform: look at its ownership, security record, fees and what the regulator says about it.
- Start small, if you choose to start at all, with an amount you can afford to lose.
- Secure your accounts: use a unique password, two-factor authentication and, for larger holdings, consider a hardware wallet.
- Keep records of your transactions, which may be needed for tax reporting.
In Türkiye, the Capital Markets Board (CMB) oversees crypto asset service providers. An entity that appears on the CMB list of entities operating in the crypto asset market is not thereby licensed or authorized. Check the CMB's own website for current information.
For tax questions, ask a qualified adviser or read your tax authority's official guidance, because rules are specific to each country. Common scams include fake support staff, copycat websites, giveaways that ask you to send coins first, and "guaranteed profit" groups. If an offer is urgent, too good to be true or asks for your seed phrase, stop and verify it independently.
Frequently asked questions
What is crypto in simple terms?
Crypto is digital money that lives on a shared computer network instead of in a bank. Ownership is recorded on a blockchain, and cryptography keeps the records secure. You hold it with keys in a wallet. Bitcoin is the best-known example, and thousands of other cryptocurrencies exist, with very different purposes and levels of risk.
Is crypto real money?
It depends on the definition. Crypto can be used to pay or send value where people accept it, so it works somewhat like money. But in most countries it is not legal tender, its price can swing widely, and it is not issued by a central bank. Many regulators treat it as an asset rather than as currency.
Who created cryptocurrency?
Bitcoin, the first major cryptocurrency, was described in a paper published on 31 October 2008 under the name Satoshi Nakamoto. The real identity of this person or group is still unknown. The Bitcoin network started on 3 January 2009. Many later projects, such as Ethereum, were created by other teams and developers.
How does cryptocurrency get its value?
Crypto has no guaranteed value. Prices come from supply and demand: how many coins exist, how many people want them, and what they can be used for. Trust in the network, news, regulation and market mood all play a part. Because these factors change quickly, prices can be very volatile, and past prices do not predict future ones.
Is cryptocurrency legal?
It depends on the country. Some allow it, some restrict it and a few ban it. In Türkiye, crypto asset service providers fall under the CMB following Capital Markets Law amendments that entered into force on 2 July 2024, and a Central Bank rule bars crypto payments. Rules change, so check official sources or a qualified adviser.
Related terms
- Blockchain
- Altcoin
- Stablecoin
- Coin vs Token
- Crypto Wallet
- Fiat Currency
- Market Cap
Sources
- Bitcoin: A Peer-to-Peer Electronic Cash System Satoshi Nakamoto (bitcoin.org)
- The Bitcoin genesis block was mined 15 years ago Unchained
- CMS Expert Guide to Crypto Regulation: Türkiye CMS
- Turkish Central Bank bans the use of crypto assets in payment Digital Policy Alert
This glossary entry is for general information and education only. It is not investment, tax or legal advice. Crypto assets are high-risk; check official sources before you act.