That’s the question everyone who’s new to crypto asks. What’s Bitcoin? What’s blockchain? What’s a cryptocurrency?
Short version: Bitcoin is a cryptocurrency and blockchain is the technology it’s built on.
Bitcoin was the first decentralised cryptocurrency. It was launched in 2009 by Satoshi Nakamoto (that’s a pseudonym for a person or group – no one knows).
Other coins launched since Bitcoin are called “altcoins” – alternative coins to Bitcoin.
Bitcoin’s called a cryptocurrency because it uses cryptography to verify transactions and secure its blockchain.
A blockchain is like an accounts book or ledger: every Bitcoin transaction gets recorded on Bitcoin’s blockchain.
Transactions are grouped into predetermined “blocks”, which are verified to confirm they’re correct, then tied onto the end of the ledger, forming a chain. Block. Chain. Blockchain.
Each block on the chain references the one before it, making the blockchain unhackable (unless you edit every block all the way back to the start).
Bitcoin’s blockchain isn’t maintained on a server somewhere. It’s maintained by every (full node) client everywhere in the world. In other words, if you install Bitcoin-qt – “Bitcoin Core”, Nakamoto’s original software that’s been updated as the coin’s grown – you maintain a copy of the blockchain.
Because the blockchain is maintained by a decentralised network of computers, no one can shut it down. How does the “Hail Hydra” thing go? Cut off one head and two will take its place.
The blockchain is a work of genius that answered a question previously thought impossible to solve in IT: how do you make online cash with no central authority to approve anonymous transactions?
And that’s what Bitcoin is. Digital cash.