Bitcoin (BTC) is the original cryptocurrency and the largest by market value. It's a Layer 1 blockchain (its own base network, not built on top of another) launched in 2009 by the pseudonymous Satoshi Nakamoto. Its job is narrow on purpose: to be a decentralized money and store of value that no company, bank or government controls. It doesn't run apps or smart contracts the way Ethereum does — the whole point is to stay simple, hard to change, and extremely secure. Only 21 million coins will ever exist, and new ones are released on a fixed schedule that halves roughly every four years (the "halving"), which is the core of the "digital gold" idea. The network is secured by proof-of-work (a huge network of computers spending real electricity to process transactions) and has never been hacked at the protocol level in over 15 years — a track record no other crypto can show.
Where it stands today: Bitcoin has moved from a fringe internet experiment to an asset that big institutions can hold. The turning point was early 2024, when the US approved spot Bitcoin ETFs — regulated funds that let banks, pension funds and ordinary brokerage accounts get exposure without touching a crypto exchange. That pulled in large, steadier flows of money that weren't there before. The most recent halving (April 2024) cut the rate of new supply again, and a growing number of public companies — plus several governments — now hold BTC on their balance sheets. On the tech side, most everyday-payment and cheaper-transaction activity happens on layers built on top of Bitcoin (like the Lightning Network) rather than on the base chain, which stays deliberately slow and expensive to keep it secure and hard to change. In short, it's the most mature, most watched and most liquid crypto there is — but it's still a young, volatile asset compared with stocks or gold.