A blockchain is a distributed ledger technology comprising a chain of individual blocks. Each block contains information about transactions that have occurred within a specific period.
It also has a unique identifier, known as a hash, which distinguishes it from other blocks in the chain.
The blocks are created through mining, which involves solving cryptographic problems.
Blockchain Immutability
The hash of each block is derived from the information contained in all previous blocks in the chain.
This property makes the blockchain tamper-resistant.
To alter a record on the blockchain, an attacker would need to change every block on every copy of the blockchain, which is extremely difficult and practically infeasible.
Therefore, blockchains are considered to be immutable and provide a secure and transparent record of transactions.
Public and Private Blockchains
Most blockchains, including popular cryptocurrencies like Bitcoin and Ethereum, are public.
This means anyone can view the transactions on the blockchain using a block explorer tool.
However, blockchain technology also allows for a certain level of user anonymity.
In addition to public blockchains, private blockchains are being explored for various business and government use cases.
Private blockchains restrict access to a select group of participants and offer more control over the network.