What Is Bitcoin? A Complete Guide to How It Works
Bitcoin is a decentralized digital currency that lets people send and receive value directly, without a bank or payment processor in the middle. It runs on a public, shared ledger called a blockchain, secured by a global network of computers rather than any single company or government. Since launching in January 2009, it has become the largest cryptocurrency by market value, though its price remains highly volatile.
How Bitcoin Actually Works
Every Bitcoin transaction is broadcast to a network of computers, called nodes, that verify it follows the rules: the sender actually has the funds, and those funds haven’t already been spent elsewhere. Verified transactions are bundled into a block and added to the blockchain, a permanent, tamper-evident record that every node keeps a copy of.
Because thousands of independent nodes hold identical copies of this ledger, there’s no central database to hack or shut down, and no single company controls the network. That’s what “decentralized” actually means in practice: less that no one is in charge, and more that everyone holding a copy of the ledger has to agree on what’s true.
Where New Bitcoin Comes From
New bitcoin enters circulation through mining. Miners compete to solve a computational puzzle, and whoever solves it first gets to add the next block to the chain and collect a reward, paid in newly created bitcoin. This process, called proof of work, is also what secures the network, since rewriting the blockchain would mean redoing an enormous amount of computational work.
That mining reward isn’t fixed forever. It cuts in half roughly every four years, an event called the halving. The reward started at 50 BTC per block in 2009, and the most recent halving, in April 2024, dropped it to 3.125 BTC. The next is expected around 2028. This built-in scarcity is designed to cap Bitcoin’s total supply at 21 million coins, a limit expected to be reached around the year 2140. The smallest unit, one hundred-millionth of a bitcoin, is called a satoshi.
Buying, Storing, and Using Bitcoin
Most people buy Bitcoin through a cryptocurrency exchange, using regular currency. What you actually own afterward is a private key: a piece of cryptographic data that proves ownership and lets you authorize transactions. Whoever controls that key controls the coins, which is the reasoning behind the common security warning “not your keys, not your coins.”
Leaving Bitcoin on an exchange is convenient but means the exchange holds the keys on your behalf, similar to keeping cash in a bank rather than a safe at home. Moving funds to a personal wallet, either software on a phone or computer, or a dedicated hardware device, gives you direct control, along with full responsibility for keeping that key safe. A lost key generally means the funds are unrecoverable; there’s no password reset.
Is Bitcoin Regulated?
Regulation varies significantly by country and continues to evolve. In the United States, spot Bitcoin exchange-traded funds were approved in January 2024, giving investors a way to gain exposure through a regular brokerage account rather than a crypto exchange, a sign of growing institutional acceptance. Other countries range from broadly permissive to heavily restrictive. Because rules differ by jurisdiction and change over time, it’s worth checking current, local regulations rather than relying on a general guide like this one for anything specific to your situation.
The Real Risks
Bitcoin’s price has moved by double-digit percentages within days multiple times in its history, and past performance doesn’t guarantee future results in either direction. A handful of other risks are worth taking seriously:
- Transactions are irreversible. There’s no chargeback or customer service line if you send funds to the wrong address or fall for a scam.
- Losing a private key means losing access to the funds permanently.
- The space attracts scams, including fake exchanges, phishing sites, and “giveaway” schemes impersonating public figures.
- Exchanges can be hacked or can fail; funds held on an exchange carry that counterparty risk.
None of this makes Bitcoin uniquely dangerous compared to other cryptocurrencies, but it does mean treating it with the same caution as any volatile, largely unregulated asset.
Bitcoin vs Other Cryptocurrencies
Bitcoin was the first cryptocurrency, and it’s generally treated as digital gold: a scarce, decentralized store of value rather than a platform for building other applications. Ethereum, the second-largest cryptocurrency, was built for a different purpose: running smart contracts and decentralized applications on top of its blockchain. Thousands of other coins exist, each with different goals, trade-offs, and track records. Our guide to the top 50 cryptocurrencies is a good next stop for comparing them, and our crypto terms glossary covers the jargon used throughout this guide.
