Cryptocurrency

A cryptocurrency is a digital asset that records ownership and transfers on a shared ledger, usually a blockchain, and uses cryptography to control who can spend it. No central bank or company keeps the official record. A network of computers holds copies of the ledger and agrees on which transactions are valid. That agreement makes it extremely difficult to counterfeit units or spend the same coin twice. In the US, regulators such as the Securities and Exchange Commission (SEC) and the Commodity Futures Trading Commission (CFTC) still oversee certain crypto activities, including the offering and trading of assets that may count as securities or commodities.

The first working cryptocurrency was Bitcoin. A person or group using the name Satoshi Nakamoto described it in an October 2008 white paper titled “Bitcoin: A Peer-to-Peer Electronic Cash System,” and the network went live in January 2009. Thousands of other cryptocurrencies have been created since then, many with purposes that go well beyond payments.

How Cryptocurrency Works

The ledger

A blockchain is a chain of data blocks. Each block holds a batch of verified transactions and a cryptographic fingerprint (a hash) of the block before it. If someone changed an old transaction, that block’s hash would change and break the link to every later block. Honest nodes would reject the altered copy. Nodes are the computers that store and check the ledger. They must agree on its contents, so no single participant can rewrite history on their own.

The “crypto” in cryptocurrency

The term refers to the cryptographic techniques that secure the system:

• Public-private key pairs. Your public key (or an address derived from it) is where others send funds. Your private key produces a digital signature proving you are allowed to spend from that address. Whoever controls the private key controls the coins.
• Hashing functions. These turn any data into a fixed-length fingerprint. Blocks are chained together with them, and some networks also use them in mining.
• Elliptic curve cryptography. This is the mathematics behind the key pairs that Bitcoin and many other networks use. It lets a signature be checked without revealing the private key.

Consensus: how the network agrees

Networks need a way to decide who adds the next block and to make cheating expensive. The two main approaches are:

• Proof of work (PoW): Miners compete to solve a computational puzzle, and the winner adds the block and earns newly issued coins plus fees. Bitcoin uses proof of work. Attacking it would require enormous computing power and energy.
• Proof of stake (PoS): Validators lock up (“stake”) the network’s coins for the right to propose and confirm blocks. They earn rewards for honest behavior and can lose part of their stake for rule-breaking. Ethereum switched from proof of work to proof of stake in September 2022, an event known as the Merge.

What happens when you send crypto

1. Your wallet software builds a transaction that names the recipient address and the amount, then signs it with your private key.
2. The transaction is broadcast to the network’s nodes, which check the signature and confirm you have enough funds.
3. A miner or validator includes it in a new block, usually prioritizing transactions that pay higher fees.
4. Once the block is added and more blocks are built on top of it, the transaction is effectively final.

There is no “undo” button. A payment sent to the wrong address generally cannot be reversed by anyone.

Worked Example: Buying, Fees and Volatility

Hypothetical figures for illustration only. They are not any platform’s fees or any coin’s price.

Assume you buy $1,000 of a cryptocurrency priced at $50,000 per coin on an exchange that charges a 0.5% fee per side (on the buy and again on the sell).

• Buy fee: $1,000 × 0.5% = $5, so $995 is converted.
• Coins received: $995 ÷ $50,000 = 0.0199 coins.

Cryptocurrencies are divisible, so you don’t need to buy a whole coin. One bitcoin divides into 100 million units called satoshis. Many platforms set a minimum order, and on small purchases fixed fees can take a large percentage of the amount invested.

Scenario A: the price rises 20% to $60,000. 0.0199 × $60,000 = $1,194 before the sell fee. Sell fee: $1,194 × 0.5% ≈ $5.97. Net proceeds ≈ $1,188.03, a gain of about $188 on $1,000 (18.8%), not 20%. The round-trip fees took roughly $11.

Scenario B: the price falls 30% to $35,000. 0.0199 × $35,000 = $696.50, minus a sell fee of about $3.48, for net proceeds of about $693. To get back to $1,000, the price would need to climb roughly 44% from $35,000, before fees.

Fees are charged on each side of a trade, so frequent trading compounds them. Losses and recoveries are not symmetrical: a 30% drop needs a much larger percentage gain to break even. Network withdrawal fees and the buy-sell spread, ignored here, add further cost.

Types of Cryptocurrency

A coin’s name does not tell you its type. Many cryptocurrencies do a specific job inside a network. Ether (ETH), for example, pays the fees that compensate Ethereum validators, and XRP, the native asset of the XRP Ledger, is designed for cross-border payments and other value transfers. Common categories include:

Some assets fit several categories, and some fit none neatly. Two other groups come up often. Stablecoins aim to hold a steady value, usually by tracking the US dollar. Meme coins are driven mainly by online communities and attention rather than a specific function.

Coins vs. tokens: A coin is the native asset of its own blockchain (BTC on Bitcoin, ETH on Ethereum). A token is issued on top of an existing blockchain through a smart contract. UNI, for example, runs on Ethereum.

How Cryptocurrency Is Used

• Payments and transfers. Value moves directly between parties without a bank in the middle. Some merchants and payment services accept crypto.
• Cross-border payments and remittances. Crypto transfers can settle faster than some traditional international transfers, though speed and cost vary by network and provider, and many services still rely on exchanges or other intermediaries.
• Decentralized applications. Smart contracts (self-executing programs on a blockchain) power lending, borrowing and trading services known as decentralized finance (DeFi).
• Staking. Holders of proof-of-stake coins can stake them to help secure the network and earn rewards.
• Investment and speculation. Many people buy crypto expecting its price to rise.

How to Buy Cryptocurrency

There are three main routes:

1. Crypto exchanges. You fund an account with cash and buy at market prices set by supply and demand. You can then leave the coins with the exchange (custodial storage) or withdraw them to your own wallet.
2. Online brokerages. Some brokers let you buy and sell selected cryptocurrencies alongside stocks. Depending on the broker, you may not be able to withdraw the coins to a wallet.
3. Spot crypto ETFs. Spot Bitcoin ETFs (approved by the SEC in January 2024) and spot Ether ETFs hold the underlying asset and trade like ordinary exchange-traded funds. You get price exposure without managing keys or wallets, but you pay the fund’s expense ratio and cannot spend the coins directly.

Custodial vs. self-custody: With a custodial account, the provider holds the private keys and you rely on its security and solvency. With self-custody (a software or hardware wallet), you hold the keys yourself. No one can freeze your funds, but no one can recover them either if you lose your recovery phrase.

Is Cryptocurrency Legal?

Cryptocurrency is legal in many countries, but the rules differ widely and keep changing. Some countries restrict or ban it, and others regulate exchanges, stablecoins or crypto advertising. Check local law before buying, trading or spending crypto.

Taxes: The IRS generally treats cryptocurrency as property, not currency. Selling, trading or spending it can trigger a capital gain or loss. Whether a gain is short-term or long-term depends on how long you held the asset. Crypto received as payment for work, or from activities such as mining or staking, is generally taxed as ordinary income. Even swapping one cryptocurrency for another can be a taxable event.

Risks of Cryptocurrency

The blockchains of major cryptocurrencies are generally secure. Most losses come from what surrounds them: prices, platforms, people and code.

• Volatility. Prices can swing sharply over short periods.
• User risk. Transactions are generally irreversible. Sending funds to the wrong address, or losing a private key, can mean permanent loss.
• Counterparty risk. If an exchange or custodian is hacked, fails operationally or goes bankrupt, customers can lose access to some or all of their assets.
• Regulatory risk. New laws on trading, taxes or usage can affect how an asset can be used and what it is worth.
• Management risk. Projects run by inexperienced or dishonest teams may never deliver on their promises.
• Programming risk. Bugs or vulnerabilities in smart contracts can be exploited, draining funds.
• Market manipulation. Less mature, less regulated markets are more exposed to coordinated trading, social media hype and large holders moving prices.
• Scams and fraud. Fake investment schemes, phishing sites and impersonation of support staff target holders directly. Legitimate support teams do not ask for your private key or recovery phrase.

Leverage adds another layer. Trading crypto derivatives with borrowed funds can lead to forced liquidation when the price moves against you, wiping out the position’s margin.

Advantages and Disadvantages of Cryptocurrency

Advantages

• Less reliance on banks and other central intermediaries
• Direct, peer-to-peer transfers that settle at any hour
• A platform for decentralized applications and financial services
• Potential for faster or cheaper cross-border payments in some cases
• A fixed or rules-based supply for some coins, set in code rather than by a central bank
• Potential investment returns

Disadvantages

• Pseudonymous rather than anonymous
• Use in illicit activity
• Concentrated ownership and mining
• High fees or resource use on some networks
• Exchanges and wallets can be hacked
• High price volatility

Disadvantages explained

Most cryptocurrencies are pseudonymous. Addresses are not names, but every transaction sits on a public ledger, and law enforcement and blockchain analytics firms can often trace activity back to individuals. Crypto has been used for money laundering, fraud and ransomware, though illegal activity is only part of overall use. Decentralization can also erode. Large funds, companies and early holders may control big shares of a coin’s supply. Mining popular proof-of-work coins now needs specialized hardware and cheap energy, so it has concentrated among industrial operators rather than individuals. The energy use of proof-of-work networks is a long-running criticism.

Cryptocurrency vs. Related Concepts

• Cryptocurrency vs. fiat money. Dollars and euros are issued by governments, are legal tender and are backed by central banks. Most cryptocurrencies have no issuer and no legal-tender status in most countries.
• Cryptocurrency vs. blockchain. A blockchain is the ledger technology. A cryptocurrency is one asset recorded on it. Blockchains can exist without a tradable coin.
• Cryptocurrency vs. a digital bank balance. Money in a bank app is a claim on a bank, recorded in the bank’s private database and usually covered by deposit insurance up to a limit. Crypto is recorded on a shared ledger and has no deposit insurance.
• Cryptocurrency vs. stocks. A share is a legal claim on a company’s assets and earnings. Most cryptocurrencies give no ownership of a business, so their price rests on supply, demand and expected use rather than on cash flows.

Learning path

1. BeforeCloud Mining
2. You are hereCryptocurrency
3. NextWho Is Satoshi Nakamoto
4. ThenASIC Miner

FAQ