Understand Bitcoin

Bitcoin fascinates, intrigues, divides. Nearly 17 years after its creation, it remains the best-known and most resilient cryptocurrency. But for many, it still feels mysterious: what is it really, how does it work, why do so many people believe in it?

This guide lays out the basics clearly. No jargon, no hype, just the concepts that matter. By the end, you'll understand what your neighbour is talking about when they mention Bitcoin, and you'll be able to decide for yourself whether the subject deserves your attention.

Bitcoin in one definition

Bitcoin is a global digital currency, with no bank or central authority, whose maximum supply is capped at 21 million×21 millionMaximum number of bitcoins that will ever exist, hard-coded in the protocol. This programmed scarcity is a founding feature. The last sat will be mined around the year 2140.See in the lexicon → units.

Three words sum it all up:

• Digital: it exists only in electronic form, like a computer file.
• Decentralised: no state, no company, no bank controls it. A network of computers spread around the world runs it.
• Scarce: its protocol guarantees there will never be more than 21 million. Compare with euros or dollars, whose supply keeps increasing.

How it works, in 3 key ideas

You don't need to understand everything overnight. Three ideas are enough for an accurate picture.

1. The blockchain×BlockchainA public, shared ledger that records every Bitcoin transaction in blocks linked together cryptographically. Each participant in the network keeps a copy.See in the lexicon → is a giant public ledger. Every Bitcoin transaction is written in a huge accounting book, shared between thousands of computers. Anyone can check it, no one can tamper with it. Once recorded, a transaction stays there forever.

2. Miners secure the network. They are companies and individuals running specialised machines to validate new transactions and add them to the ledger×Ledger, Trezor, Coldcard, BitBoxMain hardware wallet brands. Ledger Nano S Plus / X (French, the best-seller), Trezor Model T (Czech, open source), Coldcard Mk4 (Canadian, ultra-secure, Bitcoin-only), BitBox02 (Swiss, open source).See in the lexicon →. In exchange×ExchangeService that lets you buy, sell and swap cryptocurrencies against fiat money. Examples : Kraken, Coinbase, Bitstamp, Bitvavo. Most are custodial.See in the lexicon →, they receive newly minted bitcoins. This is what prevents cheating: to rewrite history, you would need to spend more electricity than all miners combined, which is economically impossible.

3. You are your own bank. To hold bitcoins, you need a wallet×WalletSoftware or device that manages your Bitcoin keys and lets you sign transactions. A wallet does not really « hold » your bitcoins, it holds the keys that prove you own them.See in the lexicon →. It's a piece of software or a small device that keeps your keys. If you manage your keys well, no one can freeze your funds or stop you from sending a payment. This is the big difference with a traditional bank.

Why Bitcoin exists

Bitcoin was born on 3 January 2009, in the middle of the global financial crisis. Its creator, who signed under the pseudonym Satoshi Nakamoto×Satoshi NakamotoPseudonym of the creator (or collective) behind Bitcoin. Active on forums from 2008 to 2011, then vanished without revealing any identity. Holds roughly 1.1 million BTC that have never moved.See in the lexicon →, wanted to build a form of money that did not depend on banks or governments.

Three observations drove him. First, traditional money is printed at will by central banks, eroding its purchasing power over time. Second, classic digital payments rely on intermediaries that can freeze an account or refuse a transaction. Third, until Bitcoin, no one had managed to create a tamper-proof digital currency without relying on a central authority.

Bitcoin offers an alternative: a currency whose rules are written in code, controlled by no one, accessible to anyone with an internet connection.

Satoshi's white paper

It all starts with a text. On 31 October 2008, Satoshi Nakamoto×Satoshi NakamotoPseudonym of the creator (or collective) behind Bitcoin. Active on forums from 2008 to 2011, then vanished without revealing any identity. Holds roughly 1.1 million BTC that have never moved.See in the lexicon → published the Bitcoin white paper, nine pages laying out the full idea: peer-to-peer electronic cash, with no bank, that solves the double-spending problem through a network and proof-of-work. Not a single line of code, just the principles, and yet all of Bitcoin is already there.