Bitcoin works through the collaboration of computers, each of which acts as a node in the peer-to-peer bitcoin network. Each node maintains an independent copy of a public distributed ledger of transactions, called a blockchain, without central oversight. Transactions are validated through the use of cryptography, preventing one person from spending another person's bitcoin, as long as the owner of the bitcoin keeps certain sensitive data secret.
Consensus between nodes about the content of the blockchain is achieved using a computationally intensive process based on proof of work, called mining, which is performed by purpose-built computers.[7]: ch. Mining consumes large quantities of electricity and has been criticized for its environmental impact.
