Bitcoin launched in January 2009 when an unknown programmer called Satoshi Nakamoto mined the first block. The first transaction sent 10 BTC to Hal Finney, an early contributor. Nobody knew if it would work. Sixteen years later it is the largest cryptocurrency by market value and a fixture on institutional balance sheets.

The supply is capped at 21 million coins. No central bank decides how many to mint. Miners compete to add blocks and receive new coins as a reward, but that reward halves roughly every four years. The last Bitcoin will not be mined until around 2140. Transactions settle on a public ledger that anyone can inspect. No one can freeze your wallet or reverse a confirmed payment. That independence cuts both ways. Lose your private key and the coins are gone forever.

Key facts

• Launched January 2009 by the pseudonymous Satoshi Nakamoto
• Supply capped at 21 million BTC
• Block reward halves approximately every four years
• First real-world purchase: 10,000 BTC for two pizzas in May 2010

Bitcoin is slow and expensive compared to modern chains. It was not built for high throughput. It was built to settle value without permission. That trade-off remains the core of the debate.