Blockchain
Also called: chain of blocks, distributed ledger
A blockchain is a shared public ledger made of blocks of transactions chained together, which miners extend and secure.
A blockchain is a large ledger of transactions copied across thousands of computers around the world. Transactions are grouped into blocks, added one after another. Each block contains the fingerprint, or hash, of the previous block: it is this link that forms the chain and gives it its name.
This chaining makes the history very hard to falsify. Changing an old transaction would change the hash of its block and break the link with all the blocks that follow. On a proof-of-work blockchain like Bitcoin's, an attacker would then have to redo the mining work for all those blocks faster than the rest of the network, which is out of reach. The network's nodes check every block and reject any that break the rules.
The miners' role is to assemble new blocks and provide the proof of work that validates them. On Bitcoin, a block is added roughly every 10 minutes. Each blockchain has its own rules: algorithm, block time, reward. Before choosing a machine, you therefore need to know which blockchain it will work on and whether that blockchain really relies on proof of work.
Our Bitcoin collection brings together the machines designed to mine on the Bitcoin blockchain, the very first in history.