What Is Bitcoin? Definition, How It Works, and How to Buy It
Last updated 04/14/2026 by
Ante Mazalin
Edited by
Andrew Latham
Summary:
Bitcoin is a decentralized digital currency that operates on a peer-to-peer network, allowing value to be transferred between parties anywhere in the world without a bank, government, or central intermediary.
It was the first cryptocurrency and remains the largest by market capitalization.
- Fixed supply: Only 21 million Bitcoin will ever exist — a hard cap encoded into its protocol that makes it mathematically scarce, unlike fiat currencies that can be printed in unlimited quantities.
- Decentralized: No single entity controls the Bitcoin network. Transactions are validated by a global network of computers using a consensus mechanism called proof of work.
- Transparent: Every Bitcoin transaction ever made is permanently recorded on a public ledger — the blockchain — that anyone can audit at any time.
- Volatile: Bitcoin’s price swings significantly. It reached an all-time high of approximately $126,000 in October 2025 before correcting roughly 27% within two months.
Bitcoin was introduced in 2009 by an anonymous developer — or group of developers — operating under the pseudonym Satoshi Nakamoto. The original white paper, published in October 2008, proposed a system for electronic cash that could operate without a trusted third party.
In the years since, Bitcoin has evolved from an obscure cryptography project into a globally traded asset held by retail investors, institutions, and sovereign wealth funds.
In January 2024, the SEC approved the first spot Bitcoin exchange-traded products in the United States — a development that marked its formal entry into mainstream regulated finance.
How Bitcoin works
Bitcoin runs on a technology called the blockchain — a distributed public ledger that records every transaction in a chain of data blocks. No single server stores this ledger. Instead, it exists simultaneously across thousands of computers worldwide, making it resistant to manipulation or shutdown by any single actor.
When you send Bitcoin to someone, the transaction is broadcast to the network. Miners — participants who contribute computing power — compete to bundle recent transactions into a new block and add it to the chain. The first miner to solve a complex mathematical puzzle earns the right to add the block and receives a Bitcoin reward for doing so.
This process is called proof of work, and it serves as Bitcoin’s security mechanism: altering any historical transaction would require re-solving the puzzle for that block and every subsequent block — a computational task that is prohibitively expensive on a network of Bitcoin’s size.
SuperMoney’s dedicated entry on Bitcoin mining covers the mechanics of how mining works, the hardware involved, and its economic incentives in detail.
Bitcoin’s supply: the 21 million cap
Bitcoin’s total supply is permanently capped at 21 million coins — a limit built into the protocol’s source code that no single party can change. As of 2025, more than 19.95 million Bitcoin have already been mined, meaning over 95% of the total supply is already in circulation, according to data from The Block.
New Bitcoin enters circulation only through mining — and the rate of new issuance is deliberately designed to decrease over time through a mechanism called the halving.
How the Bitcoin halving works
Every 210,000 blocks — approximately every four years — the reward miners receive for adding a new block is cut in half. This is the halving. The historical sequence:
- 2009 (genesis): Block reward = 50 BTC
- 2012 (first halving): Reward reduced to 25 BTC
- 2016 (second halving): Reward reduced to 12.5 BTC
- 2020 (third halving): Reward reduced to 6.25 BTC
- April 2024 (fourth halving): Reward reduced to 3.125 BTC
The halving continues until approximately the year 2140, when the final fraction of Bitcoin is expected to be mined. After that, miners will be compensated solely through transaction fees. SuperMoney’s entry on Bitcoin block rewards explains the economic implications of this declining issuance schedule.
Pro tip: Bitcoin’s smallest unit is the satoshi — named after the pseudonymous creator. One satoshi equals 0.00000001 BTC, or one hundred-millionth of a single Bitcoin. As Bitcoin’s price rises, denominating transactions in satoshis rather than whole coins becomes increasingly practical. See SuperMoney’s entry on the satoshi for conversion context.
How to buy Bitcoin
There are three primary ways individual investors access Bitcoin today, each with different trade-offs around cost, custody, and complexity.
- Cryptocurrency exchanges: Platforms like Coinbase, Kraken, and Binance allow you to buy, sell, and hold Bitcoin directly. You create an account, complete identity verification (KYC), fund it via bank transfer or debit card, and purchase Bitcoin at the current market price. Exchanges custody the coins on your behalf unless you withdraw to a personal wallet.
- Spot Bitcoin ETFs: Since January 2024, U.S. investors can buy Bitcoin exposure through exchange-traded products in standard brokerage accounts — the same way they buy stocks or index funds. The iShares Bitcoin Trust (IBIT) and Fidelity Wise Origin Bitcoin Fund are among the largest, with combined net inflows exceeding $48 billion since launch, according to SEC filings and fund disclosures. ETFs don’t give you direct ownership of Bitcoin — they give you price exposure without managing a wallet or private keys.
- Self-custody wallets: You can withdraw Bitcoin from an exchange to a hardware or software wallet you control directly. This gives you full ownership of your coins — no exchange can freeze or lose them — but places full responsibility for security on you. Losing your private key means losing access permanently, with no recovery option.
Bitcoin as an investment
Bitcoin’s investment profile is unlike any traditional asset class. It combines characteristics of a currency, a commodity, and a speculative growth asset — without fitting neatly into any category.
- Scarcity argument: Proponents compare Bitcoin’s 21 million cap to gold’s finite supply — arguing that its mathematical scarcity makes it a long-term store of value and inflation hedge, particularly as central banks expand money supply.
- Institutional adoption: The approval of spot Bitcoin ETFs in 2024 accelerated institutional entry. Institutional investors now hold approximately 24.5% of U.S. Bitcoin ETF assets under management, with corporate treasuries and hedge funds treating it as a portfolio diversifier.
- Correlation risk: Bitcoin increasingly trades as a “risk-on” asset alongside technology stocks. During equity sell-offs, Bitcoin often declines alongside the Nasdaq rather than acting as an uncorrelated hedge — limiting its portfolio diversification value in the scenarios where diversification is most needed.
- Liquidity: Bitcoin is one of the most liquid assets in the world by trading volume. The market operates 24 hours a day, 7 days a week — unlike stock exchanges with defined trading hours.
Risks of owning Bitcoin
Bitcoin carries a risk profile that is materially different from stocks, bonds, or cash. Understanding each risk before allocating capital is essential.
- Volatility: Bitcoin’s price can move 20–30% in weeks or even days. It surged to ~$126,000 in October 2025 and corrected to ~$91,000–$93,000 by December — a 27% drawdown in roughly two months. Investors who need liquidity at a specific time are highly exposed to this risk.
- Regulatory risk: Governments can change the legal status of Bitcoin, restrict exchanges, impose capital gains reporting requirements, or ban certain uses. Regulatory environments vary sharply by country and can shift with little warning.
- Custody risk: Bitcoin held on an exchange is only as safe as that exchange. Multiple major exchanges — including Mt. Gox and FTX — have collapsed, resulting in total loss of customer funds. Self-custody eliminates exchange risk but introduces the risk of losing private keys.
- No recourse: Bitcoin transactions are irreversible. Sending Bitcoin to the wrong address or falling victim to a scam has no recovery mechanism — there is no central authority to reverse the transaction or compensate losses.
- Concentration risk: A significant portion of Bitcoin supply is held by a small number of early adopters and institutional wallets. Large holders — called “whales” — can cause significant price disruption when they buy or sell.
Bitcoin vs. traditional currency
Bitcoin was designed as an alternative to government-issued fiat currency — and the two systems differ in fundamental ways.
| Feature | Bitcoin | Fiat Currency (e.g., USD) |
|---|---|---|
| Supply control | Fixed at 21 million; controlled by protocol | Unlimited; set by central banks |
| Issuing authority | None — decentralized network | Central banks and governments |
| Transaction settlement | 10 minutes average (on-chain); near-instant (Layer 2) | Seconds to days depending on method |
| Reversibility | Irreversible once confirmed | Reversible through banks and payment processors |
| Transparency | All transactions public on blockchain | Transactions private (bank-mediated) |
| Price stability | Highly volatile | Managed for relative stability |
Key takeaways
- Bitcoin is a decentralized digital currency with a hard supply cap of 21 million coins — over 95% of which have already been mined as of 2025.
- It operates on the blockchain, a distributed public ledger validated by miners through a proof-of-work consensus mechanism that makes the transaction history tamper-resistant.
- The Bitcoin halving cuts miner rewards in half every ~4 years; the most recent halving in April 2024 reduced rewards to 3.125 BTC per block.
- The SEC approved spot Bitcoin ETFs in January 2024, opening a regulated, brokerage-accessible route for investors — with combined ETF inflows exceeding $48 billion in the first year of trading.
- Bitcoin reached an all-time high of approximately $126,000 in October 2025, with a subsequent ~27% correction — illustrating the volatility that remains a defining characteristic of the asset.
- Key risks include price volatility, regulatory change, custody risk (exchange failures or lost private keys), and the irreversibility of all on-chain transactions.
Frequently asked questions
Who created Bitcoin?
Bitcoin was created by a person or group operating under the pseudonym Satoshi Nakamoto. The Bitcoin white paper was published in October 2008, and the network went live in January 2009. Nakamoto’s true identity has never been confirmed. In 2010, Nakamoto handed off development to other contributors and stopped communicating publicly.
Is Bitcoin legal in the United States?
Yes. Bitcoin is legal to buy, sell, hold, and use in the United States. The IRS treats it as property for tax purposes — meaning capital gains taxes apply when you sell, exchange, or spend it. The Financial Crimes Enforcement Network (FinCEN) requires exchanges to comply with anti-money laundering (AML) rules and collect customer identity information (KYC).
How is Bitcoin taxed?
The IRS classifies Bitcoin as property. Selling Bitcoin at a profit triggers a capital gain — taxed at short-term rates (ordinary income) if held under one year, or long-term rates (0%, 15%, or 20% depending on income) if held over one year. Using Bitcoin to buy goods or services is also a taxable event if the Bitcoin has appreciated in value since you acquired it.
What is the difference between Bitcoin and other cryptocurrencies?
Bitcoin was the first cryptocurrency and remains the largest by market capitalization. It has the longest track record, the most liquidity, and the broadest institutional recognition. Other cryptocurrencies — collectively called “altcoins” — include Ethereum, Solana, and thousands of others, each with different use cases and technical designs.
Bitcoin’s focus is narrow: a decentralized store of value and payment network. Bitcoin Cash, a 2017 fork of the original Bitcoin protocol, attempted to scale transaction throughput; see SuperMoney’s entry on Bitcoin Cash for that history.
What is a Bitcoin wallet?
A Bitcoin wallet is software or hardware that stores the private keys needed to access and transact Bitcoin on the blockchain. Wallets don’t actually hold Bitcoin — Bitcoin exists on the blockchain. The wallet holds the cryptographic key that proves ownership and authorizes transfers.
Losing the private key means losing access to the Bitcoin permanently, with no recovery mechanism.
Can Bitcoin reach zero?
Theoretically yes — any asset can lose all its value. In practice, Bitcoin would need a catastrophic combination of complete loss of user confidence, a fatal technical vulnerability in the protocol, or coordinated global regulatory prohibition.
Despite numerous predictions of its demise over 15+ years, Bitcoin has recovered from multiple drawdowns of 80% or more. That history does not guarantee future performance, but it does illustrate the asset’s resilience relative to expectations.
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