The first Bitcoin transaction occurred in 2009.
Bitcoin’s network began on January 3, 2009, when Satoshi Nakamoto mined the genesis block. The first widely recognized Bitcoin transaction between two people followed nine days later, on January 12, 2009. Nakamoto sent 10 bitcoins to Hal Finney, an early programmer, cryptographer, and one of Bitcoin’s first users.
This date is different from the first famous purchase made with Bitcoin. On May 22, 2010, Laszlo Hanyecz paid 10,000 BTC for two pizzas, creating the event now known as Bitcoin Pizza Day. That was the first well-known commercial transaction involving physical goods, not the first Bitcoin transaction overall.
The wording can also cause confusion because the genesis block contains a coinbase transaction awarding Nakamoto 50 BTC, but those coins are generally treated as unspendable. For standard trivia purposes, the first person-to-person Bitcoin transfer is the canonical event, and it happened in 2009. Bitcoin’s software was released publicly on January 9 of that year.