The model that describes how data is written to a blockchain is often referred to as the “consensus mechanism.” A consensus mechanism is a protocol or algorithm that ensures all participants in a blockchain network agree on the state of the ledger, including the order and validity of transactions.
Different consensus mechanisms have developing to address various needs and constraints. Some of the most well-known consensus mechanisms include:
Proof of Work (PoW):
This is the consensus mechanism that Bitcoin uses. Miners compete to solve complex mathematical puzzles, and the first one to solve it gets to add the next block of transactions to the blockchain. This requires a lot of computational power and energy.
Proof of Stake (PoS):
In PoS, validators (participants who holding a certain amount of cryptocurrency) choses to create new blocks and validate transactions on the amount of cryptocurrency they put and are willing to “stake” as collateral.
Delegated Proof of Stake (DPoS):
Similar to PoS, DPoS allows token holders to vote for a set of delegates who are responsible for validating transactions and creating blocks. The number of delegates is usually making the process more efficient.
Proof of Authority (PoA):
In PoA, validators not choses a computational power or stake tokens, but rather their identity and reputation. It’s often uses in private or consortium blockchains.
Proof of Space (PoSpace) and Proof of Capacity (PoC):
These mechanisms use the amount of storage space participants dedicate to the network as a way to secure the blockchain and create new blocks.
Proof of Elapsed Time (PoET):
This mechanism designs to be energy-efficient. Participants wait for a randomly generated period of time, and the first one to finish gets to create the next block.
Byzantine Fault Tolerance (BFT):
BFT mechanisms aim to reach consensus even in the presence of malicious actors. Practical Byzantine Fault Tolerance (PBFT) and variants are examples of such mechanisms.
Hybrid Consensus:
Some blockchain networks use a combination of different consensus mechanisms to balance efficiency, security, and decentralization. For example, a network might use PoW for initial block creation and PoS for subsequent validations.
These mechanisms ensure that all participants in a blockchain network agree on the history and validity of transactions, ultimately defining how data is written to the blockchain. The choice of consensus mechanism depends on the goals, security considerations, and use case of the blockchain network.