A blockchain is a form of DLT with generally three fundamental parts: a note, block, and chain. A note is the record of a transaction or ‘a bundle of records’. A note is stored in a block that also contains a timestamp and links to the next block. Because of this linkage, the blocks become immutable and tamper-proof with the usage of cryptography and consensus mechanism. By connecting the individual blocks together, the chain is created.
An essential part of the security of blockchains is also so-called cryptographic “hashes”. Cryptographic hashes are complex algorithms that use the data of previous transactions to generate a unique hash value. Even the smallest change to the blockchain (even a single digit) will change the hash value.
Blocks are added to the chain, based on the rules of the system called a consensus algorithm. This mechanism is part of the process that ensures data synchronisation across the network and requires approval by specific participants before the ledger will update with new blocks of information. The changes are reflected through the internet in minutes, or in some cases, seconds.
In a sense, blockchain is an unchangeable shared repository of information. This means that parties can trust the data even without the authority to validate them.
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