Bitcoin (BTC)
Bitcoin is the first and largest cryptocurrency, launched in 2009 as decentralised digital money with a fixed supply of 21 million.
In depth
It runs on Proof of Work, produces a block about every ten minutes and has never been hacked at the protocol level. Its design favours security and predictability over speed or programmability. Many people treat it as "digital gold" — a store of value rather than a payment rail.
Why it matters
BTC sets the tone for the entire market; most assets still move in its shadow.