Cryptocurrency: The Complete Guide

What Is Cryptocurrency?

A cryptocurrency is a digital asset recorded on a blockchain — a shared ledger maintained by a network of computers rather than by any single company or government. Because there is no central authority, no one entity can freeze your balance, reverse a transaction, or print more coins at will (unless the protocol's own rules allow it). Ownership is proven by a private cryptographic key, which is essentially a long, unique password.

The word "currency" is historically loaded. Economists typically look for three qualities in money: a medium of exchange, a store of value, and a unit of account. Most cryptocurrencies aim at one or two of those functions; few fully satisfy all three in everyday commerce. Readers will find economists and market participants still debating these definitions actively.

What is not debated: cryptocurrencies trade like financial assets. They have prices quoted in major currencies (usually US dollars), they have markets, and they move — sometimes dramatically. You can follow live prices for hundreds of them on our crypto data page.

How Crypto Differs From Every Other Asset Class

Every other asset class covered on this site comes with an issuer, a regulator, or both. A stock represents a claim on a company's earnings. A bond is a loan contract with a borrower. A commodity like crude oil has physical supply chains and government oversight. Cryptocurrency has none of these anchors. Its price reflects only what participants collectively believe it is worth at this moment.

That structural difference produces several practical distinctions traders and investors should understand before looking at any price column.

24/7/365 Markets

Stock exchanges close at the bell. Bond markets observe holidays. Currency markets pause on weekends. Crypto markets never close. A price quoted on Monday morning may be wildly different from Friday's close — and there is no "close" in the traditional sense. This is why percentage-change columns on crypto data pages use a fixed 24-hour window rather than a market session.

Custody and Self-Sovereignty

When you own shares in a brokerage account, a regulated custodian holds them on your behalf. With crypto, coins can be held in cold storage — offline devices controlled entirely by the holder — or on an exchange. Exchanges, wallets, and custody work very differently from brokerage accounts. If a private key is lost, the coins are gone permanently; there is no password-reset mechanism built into the blockchain.

Settlement Is Final and Fast

A stock trade settles in one or two business days because banks and clearinghouses need time to transfer legal ownership. A Bitcoin transaction is typically confirmed within minutes and is irreversible once buried under several subsequent blocks. There is no dispute process, no chargeback, and no central authority to appeal to. This finality is a feature for some use cases and a risk for others.

Volatility

Volatility — the speed and size of price swings — in crypto has historically been far higher than in most other asset classes. Double-digit percentage moves in a single day are not unusual during active periods. This reflects thin liquidity at times, the absence of circuit breakers, round-the-clock trading, and the fact that sentiment can shift faster than any fundamental anchor can catch up. Readers can explore this in depth in our guide on crypto volatility and market cycles.

The Major Categories of Crypto Assets

The phrase "crypto" covers thousands of distinct assets. They are not all the same thing. Here is a plain-English map of the landscape.

Bitcoin

Bitcoin was the first cryptocurrency, launched in 2009. Its protocol hard-caps total supply at 21 million coins. Roughly every four years, an event called a halving cuts the rate at which new Bitcoin is created by half. Economists and analysts often watch halvings as supply-side events, though market reactions have varied significantly across each cycle.

Ethereum and Smart-Contract Platforms

Ethereum introduced the idea of a smart contract — self-executing code stored on the blockchain that runs automatically when conditions are met. This made the blockchain programmable, enabling decentralized applications for lending, trading, and more. Gas fees — the cost paid to validators for processing transactions — fluctuate with network demand and are one of the most-watched metrics on Ethereum.

Stablecoins

Stablecoins are tokens designed to maintain a fixed value, usually one US dollar. They serve as the dollar-denominated "cash" layer inside crypto markets — traders move into stablecoins to reduce exposure without leaving the blockchain ecosystem. The risk of a depeg — losing that fixed value — became widely understood after several high-profile failures, including the collapse of the algorithmic stablecoin TerraUST in 2022.

Altcoins and Tokens

Altcoins are any coins other than Bitcoin. Some are forks (copies with modifications) of Bitcoin's code; others are entirely independent. Tokens differ from coins in that they are built on top of an existing blockchain rather than running their own network. The distinction matters for understanding settlement, fees, and which blockchain's health affects the token's usability.

How Crypto Is Priced and Quoted

Crypto prices are almost universally quoted in US dollars, though pairs against euro, British pound, Japanese yen, and other currencies exist on major exchanges. The price you see on a data page is typically the last traded price on the largest liquid exchanges at that moment — unlike stocks, there is no single official exchange, so aggregators blend data from multiple venues.

Market capitalization — called "market cap" — is the total number of coins in circulation multiplied by the current price. Suppose a coin has 100 million tokens in circulation and trades at $10 per token; its market cap is $1 billion (that's an illustrative example, not a real asset). Market cap is the standard way to rank cryptocurrencies. Our guide to crypto market cap and dominance explains how Bitcoin Dominance — Bitcoin's share of total crypto market cap — is read as a sentiment indicator.

Circulating supply (coins currently in the market) and fully diluted valuation (market cap if every future coin were already in circulation) are two different numbers. When they diverge sharply, it signals that a large portion of future supply is still to be issued — a factor analysts watch when evaluating long-term dilution risk.

Risk, Structure, and What Makes Crypto Unique to Watch

Understanding the risks built into crypto's structure is part of understanding the data, not a moralizing footnote. Several structural features produce the price behavior you see in the charts.

No Intrinsic Cash Flows

A stock's price can be anchored, at least partly, to earnings estimates and dividend expectations. A bond's price is anchored to its contractual payments. Most cryptocurrencies produce no cash flows for their holders — there is no coupon, no earnings per share, no landlord collecting rent. Prices reflect expected future demand, network utility, scarcity mechanics, and sentiment. This is why crypto is often described as purely reflexive: price itself becomes a driver of narrative, which drives more price movement.

Liquidity Varies Enormously

Liquidity — how easily an asset can be bought or sold without moving the price — is deep for Bitcoin and Ethereum on major exchanges, but it falls off sharply for smaller coins. A coin ranked #500 by market cap may have a bid-ask spread dozens of times wider than Bitcoin's. Thin liquidity amplifies price swings in both directions and makes large trades difficult to execute without significant slippage.

Leverage and Liquidations

Crypto derivatives markets — futures and perpetual contracts — allow traders to use leverage, meaning they control a position larger than their actual capital. When prices move against a leveraged position beyond a threshold, an automatic liquidation closes it forcibly. Cascading liquidations have historically accelerated sharp sell-offs, turning a modest decline into a rapid crash within hours. Traders typically watch reported liquidation volumes as a real-time signal of market stress.

Regulatory and Custody Risk

Regulatory frameworks for crypto vary dramatically by country and continue to evolve. Exchange failures — most famously the collapse of FTX in 2022 — have demonstrated that coins held on a centralized exchange are subject to that exchange's solvency. Self-custody removes counterparty risk from an exchange but introduces the responsibility of securing private keys personally.

How to Read Crypto Data

The data columns on a crypto page differ in important ways from stocks or bonds. Here is what each one typically represents.

• Price: Last traded price in USD (or another quote currency), aggregated across major exchanges. Because markets never close, this updates continuously.
• 24h Change (%): Percentage move from exactly 24 hours ago — not from a market open, because there is none. This is the standard measure of short-term performance for crypto.
• 7d / 30d Change (%): Rolling windows, not calendar weeks or months. Useful for smoothing out the noise of single-day swings.
• Market Cap: Circulating supply × current price. Refreshes with every price tick.
• Volume (24h): Total value traded across tracked exchanges in the last 24 hours. High volume on a big price move suggests broad participation; low volume can signal that a move may be fragile.
• Dominance (%): Shown for Bitcoin and Ethereum — their market cap as a share of all crypto. Historically, rising dominance during downturns has indicated that participants are rotating toward perceived quality.

For a deeper explanation of percentage-change columns across all asset classes, see Day, Week, YTD, YoY: Reading Percentage Moves. For context on how crypto fits alongside other markets, What Are Financial Markets? is a good starting point.

Where to Go Next

This guide is the entry point. Each major topic has its own deep dive in the guide library.

• What Is a Blockchain? — The technical foundation, explained without jargon.
• Bitcoin: Supply, Halvings and Mining — How Bitcoin's economics work.
• Ethereum and Smart Contracts — Programmable blockchains and why they matter.
• Stablecoins: Crypto's Dollars — How they hold their peg, and what happens when they don't.
• Crypto Market Cap and Dominance — How to read the headline size numbers.
• DeFi: Lending, DEXs and Yield — The parallel financial system built on blockchains.
• Crypto Volatility and Market Cycles — Why crypto moves in historically dramatic patterns.

Live prices, market caps, and 24-hour volume for hundreds of assets are on the crypto data page. The economic calendar also tracks macro events — central bank decisions, inflation releases — that have historically influenced crypto markets alongside traditional assets.