Bitcoin
Bitcoin is the first cryptocurrency, launched in 2009 by an author writing as Satoshi Nakamoto. It runs without a bank or intermediaries: a network of independent computers verifies transactions, and there will never be more than 21 million coins.
How it works
Every transfer is written into a shared ledger, the blockchain, copies of which are kept by thousands of nodes worldwide. New entries are gathered into blocks roughly every ten minutes, and each block references the one before it, so rewriting the past cannot go unnoticed.
The right to write the next block is contested through mining: computers grind through candidates until one fits, spending electricity to do it. The winner is paid in new coins, which is the only way coins come into existence.
Ownership comes down to keys. Coins do not sit in a wallet; the blockchain records which address they belong to, and a private key proves the right to move them. A lost key means lost coins, with nobody to appeal to.
How many coins there are
Issuance is set in code and halves roughly every four years.
| Hard cap | 21,000,000 BTC |
| Block reward since 2024 | 3.125 BTC |
| Blocks per day | ≈ 144 |
| New coins per day | ≈ 450 BTC |
The last coin will be mined around 2140. Bitcoin divides down to one hundred-millionth of a coin, a unit called a satoshi, and the network actually counts in those.
What to keep in mind
- It is not anonymousAddresses carry no name, but the full transfer history is public forever. Tie an address to a person once and an analyst sees everything else too.
- Transfers are finalSend to the wrong address and there is no undo: the network has no party able to perform one.
- Volatility is the baselineDaily moves of 5–10% are ordinary, and drawdowns of 70% from a peak have happened in every market cycle.
- The fee ignores the amountYou pay for space in a block, not for the size of the transfer: sending $50 and $5m costs about the same.