What are the common types of consensus mechanisms for L1 blockchains?

Proof of Work (PoW): Nodes compete for accounting rights by calculating complex mathematical problems. The nodes that are the first to calculate the correct answers will obtain accounting rights and receive rewards. Bitcoin, like Bitcoin, uses the PoW mechanism, its advantage is that it is completely decentralized and has high security. The disadvantages are huge energy consumption, slow transaction processing speed and low efficiency. For example, Bitcoin generates a new block every 10 minutes on average, and its energy consumption is comparable to that of a medium-sized country.

Proof of Stake (PoS): Accounting rights are allocated based on the amount and time the node holds cryptocurrency. The more equity you hold and the longer you take, the greater the probability of obtaining the right to bookkeeping. Ethereum’s transition from PoW to PoS is aimed at solving the problem of energy waste. PoS has low energy consumption and fast transaction confirmation speed, but there is a Matthew effect of "the richer is richer", and initial equity distribution is also difficult to be fair.

Delegated Proof of Stake (DPoS): The token holder votes to select a certain number of trustees (super nodes) to be responsible for the bookkeeping. These trustees take turns to generate blocks, and if any node does evil, they will be kicked out by votes. EOS adopts the DPoS mechanism, which has the advantages of fast transaction speed, high efficiency and low energy consumption. However, its degree of decentralization is relatively weak, and there is a risk of trustees' conspiracy.

Practical Byzantine Fault Tolerance (PBFT): PBFT is a consensus algorithm based on messaging that tolerate a certain number of Byzantine nodes (malicious or failed nodes). It does not require nodes to perform a large amount of computation and reach a consensus through message interaction between nodes. It is widely used in alliance chains, such as R3 Corda. The advantage is that transaction confirmation speed is fast and efficient; the disadvantage is that as the number of nodes increases, communication overhead increases, and scalability is limited.

Authorized Byzantine Fault Tolerance (dBFT): dBFT is improved on the basis of PBFT, introducing an equity mechanism, and participating in consensus through nodes holding equity. Like the NEO blockchain, dBFT is used. It combines the efficiency of PBFT and the PoS's rights concept, which can ensure a certain degree of security while improving efficiency and reducing communication costs. But it also faces the challenge of scalability when the number of nodes increases.

Proof of Elapsed Time (PoET): PoET is a consensus mechanism proposed by Intel, based on Trusted Execution Environment (TEE). The nodes compete for the accounting rights by waiting for a random time, and blocks can be generated when the time comes. It consumes low energy, fast transaction processing speed, and has good scalability. It is often used in some alliance chain scenarios that require high performance and energy consumption, but rely on specific hardware support and the application scope is relatively limited.

Proof of Importance (PoI): Accounting rights are allocated according to the comprehensive importance of nodes. Importance considerations include the transaction volume of nodes, holding assets, connection degree with other nodes, etc. This mechanism encourages nodes to actively participate in network activities. It balances decentralization and efficiency to a certain extent, but the design of the importance evaluation algorithm is relatively complex and there may be inaccurate evaluation.