Blockchain
The blockchain is Bitcoin's public, immutable ledger that records every transaction ever made on the network. It consists of an ordered chain of blocks, each cryptographically linked to the previous one, creating a tamper-evident history of all bitcoin movements.
How It Works
Bitcoin's blockchain is a chain of data blocks where each block contains a set of validated transactions and a cryptographic hash of the previous block. This chaining creates an immutable record — altering any historical block would change its hash, breaking the link to every subsequent block. The cost of rewriting history grows exponentially with each new block added, making confirmed transactions practically irreversible.
Every full node on the network maintains a complete copy of the blockchain, independently verifying every block and transaction against the consensus rules. There is no master copy — every node is equal. When a new block is mined, it propagates across the network and each node validates it before adding it to their local copy. This redundancy makes Bitcoin extraordinarily resilient.
The term "blockchain" has been co-opted by countless marketing campaigns for unrelated technologies. Bitcoin's blockchain is unique because it is secured by real proof-of-work, is truly decentralized, and has operated continuously since January 3, 2009 without any downtime or administrator intervention.
Key Points
- Each block is cryptographically linked to the previous one via hash pointers
- The full blockchain is independently stored and verified by every full node
- Altering historical transactions would require re-mining every subsequent block
- Bitcoin's blockchain has operated with 100% uptime since its genesis block in 2009
- Always verify using your own node rather than trusting third-party explorers