What Is Bitcoin? The Original Cryptocurrency Explained
Bitcoin is the first cryptocurrency, launched in 2009, and remains the largest by market value. It is a decentralized digital money that lets people send value directly to each other over the internet without a bank, secured by a global network of computers rather than any single company or government.
How bitcoin works
Bitcoin runs on a blockchain, a shared ledger maintained by thousands of computers worldwide. Transactions are confirmed through proof of work, where miners spend computing power to validate blocks and are rewarded with new bitcoin. This design makes the record extremely costly to tamper with. For the underlying mechanics, see our blockchain guide.
Key facts
| Property | Detail |
|---|---|
| Launched | 2009 |
| Maximum supply | 21 million coins |
| Consensus | Proof of work |
| Smallest unit | Satoshi (0.00000001 BTC) |
| Primary use | Store of value and payments |
Why the 21 million limit matters
Bitcoin’s supply is capped at 21 million coins, and the rate of new issuance halves roughly every four years in an event called the halving. This built-in scarcity is the main reason supporters describe bitcoin as digital gold, a hedge against the unlimited printing of traditional money.
What bitcoin is used for
- A long-term store of value held by individuals and institutions.
- Payments and transfers that settle without a bank.
- A reserve asset that other crypto markets are priced against.
How to own bitcoin
You can buy bitcoin on an exchange and hold a fraction of a coin. Follow our step-by-step how to buy bitcoin guide, then move it to a wallet you control using our crypto wallets guide.
Frequently asked questions
Is bitcoin a good investment? Bitcoin is volatile and not guaranteed to rise. Many treat it as a long-term, high-risk holding rather than a sure bet. Only invest what you can afford to lose.
How many bitcoins are left? New bitcoin is still being mined toward the 21 million cap, which is expected to be reached around the year 2140 due to halvings.
Can bitcoin be shut down? Because it runs across a decentralized global network, there is no single point to shut down, which is a core part of its design.
Related reading
Compare bitcoin with the second-largest network in what is ethereum, and follow the latest in our news section.