A blockchain links ordered blocks of data. Consensus mechanisms help participants agree on valid history under stated assumptions. Forks can reflect temporary competing histories or deliberate changes in rules.
Immutability is not an absolute promise for every chain or application. Understand the network’s finality model, concentration and upgrade process. An application can also depend on external data or administrators even when transactions are recorded on a blockchain.
Worked example
An on-chain record can prove that data was submitted at a point in the record. It cannot by itself prove that an off-chain warehouse actually held the goods described.
Check your understanding
Does a blockchain entry prove a real-world statement is true?
Show explanation
No. The quality of the external information remains a separate issue.
Progress is stored on this device.