Understanding Types of Blockchain Consensus Mechanisms 101 Guide

Understanding Types of Blockchain Consensus Mechanisms 101 Guide

13 min read

Blockchain technology is making waves, not just in the realm of cryptocurrencies like Bitcoin and Ethereum but also in various organizational applications – from securing data to verifying investor identities. What makes these networks tick? The answer lies in consensus algorithms. These algorithms are the linchpin that ensures all nodes in a decentralized network are synchronized and that transactions are legitimate.

You’ve likely encountered the Proof of Work (PoW) consensus algorithm popularized by both Bitcoin and Ethereum networks. While PoW has its merits, it’s gradually being replaced by more energy-efficient mechanisms, offering different consensus algorithms for various needs.

So, why should you learn about blockchain consensus mechanisms? Because they’re the backbone of any blockchain network. They influence key performance indicators such as transaction speed and security. Whether you’re an organization aiming to secure data or a blockchain developer looking to optimize transaction fees, your chosen consensus algorithm can make or break your project.

Ready to get started? Let’s dive into the various types of blockchain consensus mechanisms and assess their pros and cons.


What is Consensus Mechanism in Blockchain?

pieces of puzzle

Briefly imagine a room full of people who must agree on something – sounds chaotic, right?

Now, think of a consensus mechanism as the rulebook that helps everyone in that room reach a mutual agreement.

In the context of blockchain networks, this “rulebook” is a sophisticated program that automates the process of reaching agreement among network participants.

Consensus mechanisms are the backbone of decentralized networks. They’re the automated referees that ensure all network nodes are on the same page before any updates are made to the blockchain. This is crucial for preventing issues like double-spending and Sybil attacks, where bad actors could potentially manipulate the network.

The beauty of these mechanisms is that they’re entirely automated and programmed to execute flawlessly, instilling trust in the technology rather than relying on a third party.

Bitcoin, the OG of blockchain, was the first to implement the Proof of Work (PoW) consensus mechanism back in 2009. However, the landscape has evolved, introducing other consensus mechanisms with different advantages and disadvantages.


How Does Consensus Work?

So, you’re probably wondering, “How does this whole consensus thing actually work?” In a decentralized network, it’s not as simple as one person calling the shots. Instead, it’s a collective decision-making process involving multiple network participants.

Consensus algorithms usually require a majority – often at least 51% – of nodes in the network to agree on a proposed change. If this majority is reached, the network updates with the new change. If not, the proposal is rejected and returned to the drawing board.

Think of it like a democratic voting system. Just as a bill needs a majority vote to become law, a proposed network update needs a majority nod from the network participants to take effect. This mutual agreement ensures that no single entity has too much power, maintaining the integrity and security of the entire network.


What are the Types of Blockchain Consensus Mechanisms?

types of consensus mechanisms in blockchain

Let’s dive into the heart of blockchain networks: consensus algorithms. These are the rules of the game, dictating how transactions are validated, and new blocks are added to the chain.


Proof of Work (PoW)

bitcoin mining

First up is Proof of Work, the original consensus algorithm that came into existence with Bitcoin. Here, miners – acting as network validators – compete to solve complex cryptographic puzzles. The first to solve it gets the privilege of adding a new block to the blockchain, validating transactions, and being rewarded with freshly minted crypto.


  • Security: The high computational power required makes it a tough nut for hackers to crack.
  • Authenticity: With PoW, altering any block is practically impossible, ensuring each transaction’s integrity.
  • Environmental Concerns: The high energy consumption isn’t exactly a win for Mother Earth.
  • Cost: The financial capital needed for specialized hardware and electricity can be hefty.
  • Speed: The PoW algorithm isn’t known for its speed; transaction fees can also be higher.

Other blockchain networks like Litecoin also rely on PoW. However, Ethereum recently transitioned to Proof of Stake to become more energy-efficient and speed up transaction times.


Proof of Stake (PoS)

in store pos for crypto

So, you know about Proof of Work, but let’s talk about its eco-friendly cousin, Proof of Stake (PoS). In PoS, you don’t need to solve complex puzzles; instead, you can become a validator by simply locking up some of your tokens for a set period. The more tokens you lock up, the better your chances of being chosen to create the next block on the blockchain.


How it Works

Becoming a Validator: Lock up your tokens and become a validator! The more you stake, the higher your odds of being chosen to produce the next block.

Rewards: Validators are usually rewarded with transaction fees from the block they’ve created or a specific number of newly minted coins.


  • Energy Efficiency: PoS is a green alternative to PoW, consuming significantly less energy.
  • Accessibility: No need for specialized hardware; your regular PC will do just fine.
  • Speed: PoS-based blockchains like Flow and Avalanche boast transaction speeds of over 1,000 and 4,500 tps, respectively.


  • Centralization Risks: Validators with more staked tokens have more influence, potentially leading to centralization.
  • Locked Funds: Your staked tokens are locked for a period, making them untradeable regardless of market conditions.

Avalanche, Polygon, and Tezos are some popular blockchains using PoS, each with unique features and community backing.


Delegated Proof of Stake (DPoS)

delegated proof of stakes

In DPoS, you’re not just staking your tokens; you’re also voting for delegates who will be responsible for producing new blocks. Your vote’s weight is directly proportional to the number of tokens you’ve staked.


How it Works

Staking and Voting: Stake your tokens and cast your vote for a delegate. The more you stake, the heavier your vote.

Delegate Selection: The delegate with the most votes gets the honor of producing new blocks.

Rewards: Like in PoS, delegates are rewarded with transaction fees or a specific number of new coins.


  • Speed: DPoS can handle a staggering 2,000 to 8,000 transactions per second, making it one of the fastest blockchain consensus mechanisms.
  • Energy Efficiency: DPoS is even more energy-efficient than PoS, making it a green choice for blockchain enthusiasts.
  • Security: Real-time voting allows for quick action against malicious delegates, enhancing network security.


  • Centralization Risks: Delegates could form cartels, leading to a more centralized network.
  • Security Concerns: Fewer active users make the network more susceptible to a 51% attack.
  • Power Imbalance: Those with more staked tokens have greater influence, which could be problematic.

WAX, a blockchain often used for NFT marketplaces, can perform around 8,000 transactions per second and is 125,000 times more energy-efficient than Bitcoin and Ethereum, thanks to DPoS.

Tron, Steem, EOS, and WAX are some of the well-known blockchains operating on DPoS. They are lauded for their high performance and sustainability.


Proof of Authority (PoA)

When it comes to blockchain consensus mechanisms, Proof of Authority (PoA) stands out as a unique and highly secure option, especially for private and permissioned blockchain networks. In PoA, validators stake not just tokens but their own identity and reputation.


How it Works

Identity Staking: Validators stake their identity and reputation, rather than coins.

Limited Validators: The algorithm selects a limited number of nodes responsible for validating transactions and maintaining the network.

Special Software: Validators use specialized software to monitor the network, so there’s no need for constant manual oversight.


  • Energy Efficiency: PoA doesn’t require high computational power, making it eco-friendly.
  • Security: Validators are vetted individuals, reducing the risk of network attacks.
  • Speed: PoA offers fast and predictable transaction times, averaging about five seconds per block.


  • Limited Participation: Only those with an established reputation can become validators, making it less accessible for the average person.
  • Questionable Decentralization: The limited number of validators contradicts the principle of decentralization.

Microsoft Azure uses PoA in its Ethereum-powered cloud computing system to streamline the tracking of aircraft parts for GE Aviation.


Popular PoA Blockchains

VeChainThor: Promotes mass public adoption of blockchain for business, particularly in supply chains and NFT marketplaces.

Hyperledger Besu: Part of the Hyperledger project, it employs both PoW and PoA algorithms and is ideal for supply chain industries.


Proof of History (PoH)

Ever heard of a blockchain that has its own internal clock? That’s exactly what Proof of History (PoH) brings to the table. Developed by Anatoly Yakovenko, co-founder of the Solana project, PoH is a blockchain consensus algorithm game-changer.

In the world of blockchain, time is of the essence. Unlike traditional blockchains that rely on multiple validators to agree on transaction times, PoH has a unique approach.


How it Works

Internal Clock: Each Solana validator has its own internal clock, encoded through a SHA-256, sequential-hashing verifiable delay function (VDF).

Cryptographic Proof: Every time validators communicate, a proof of the message’s relative order and time is recorded on the network ledger.

Efficiency: This eliminates the need for waiting on sequential block confirmations, making transactions faster and more efficient.


  • High Throughput: PoH can handle up to 65,000 transactions per second.
  • Low Cost: The transaction cost is a mere $0.00025.
  • Operational Efficiency: By eliminating third-party services for timestamps, PoH saves both time and operational costs.
  • Hardware Requirements: To become a validator in a PoH network, you’ll need hardware that meets strict specifications, making it costly.
  • Centralization Risks: Solana, the only PoH-based blockchain, has 21 validators controlling more than 33% of the total stake, raising concerns about potential collusion.

Solana’s SOL token is in the top 10 cryptocurrencies by market cap, and its 24-hour trading volume is in billions. The blockchain hosts over 350 solutions, including DeFi platforms and NFT marketplaces.


Proof of Capacity (PoC)

In Proof of Capacity (PoC), the focus shifts from computational power to available storage capacity for mining activities within a decentralized network. Instead of solving complex equations in real-time, miners pre-calculate a range of potential nonce and block hashes, storing them on their disk.

When it’s time to mine, these pre-computed hash files are uploaded to the network. This approach streamlines the process, making block validation and addition to the blockchain notably quicker.


How it Works

Storage Over Power: Unlike Proof of Work (PoW), which relies on computational power, PoC uses available hard drive space on a miner’s device.

Pre-stored Solutions: Before mining begins, a list of possible cryptographic solutions is stored on the hard drive. The more storage you have, the more solutions you can store.

Mining Rewards: The miner with the matching hash value for a new block wins the mining reward. It’s like a storage-based lottery!


  • Easy Setup: All you need are hard disks to plot nonces. No special hardware or ASICs are required.
  • Highly Decentralized: The low entry barrier means more people can mine, leading to a more decentralized network.


  • Grinding Attacks: Miners can manipulate the chain to always request hashes in their nonces, thereby mining more and getting more rewards.
  • Space Privilege: Those with larger hard disks have an unfair advantage as they can store more solutions.

PoC was designed to be energy-efficient, avoid the pitfalls of PoW, and prevent the hoarding seen in many Proof of Stake (PoS) systems.

Burstcoin, Storj, Chia, and SpaceMint are some of the blockchains operating on PoC


Proof of Activity (PoA)

Proof of Activity (PoA) is a combination of PoW and PoS consensus mechanisms. The process starts with miners performing complex calculations to create an initial empty block. This block contains the header details and the address where the mining rewards will go.

Next, one of these empty blocks is selected, and the criteria for this selection is the number of tokens held by the miner in their account. Once chosen, the miner who created that particular empty block can populate it with transactions. Validators within the network then authenticate these transactions.


How it Works

Mining + Staking: PoA combines the mining aspect of PoW with the staking element of PoS. Miners create new blocks, but these blocks are essentially empty templates.

Validator Selection: The transaction title in the block is used to randomly select a validator node to sign and confirm the block. Only token holders can be validators.

Reward Distribution: Both miners and validators share the network security fee, making it a win-win for everyone involved.


  • Reduced 51% Attack Risk: The random selection of validators makes it hard to predict who will sign the next block, reducing the risk of a 51% attack.
  • Balanced Network: The competition among miners and validators ensures a balanced network, where no single party has too much power.


  • Energy Consumption: Like PoW, PoA still requires significant energy during the mining phase.
  • Wealth Concentration: Major token holders still have a higher chance of signing new transactions and accumulating rewards, similar to PoS.

PoA is not to be confused with Proof of Authority, even though they share the same abbreviation.

Decred and Espers are two blockchain projects that use Proof of Activity.


Proof of Importance (PoI)

The Proof of Importance (PoI) consensus algorithm takes the Proof of Stake model a step further. Unlike Proof of Stake, which primarily focuses on the amount of assets staked by validators, PoI evaluates a node based on three key factors:

  • The balance in the account.
  • The frequency of transactions made within the network.
  • The volume of each transaction.

These criteria determine the “importance” of an account or node, encouraging users to hold assets and actively transact with them.


  • Resilient to Sybil Attacks: The PoI scoring system makes it prohibitively expensive for malicious actors to operate multiple fake nodes, thereby safeguarding the network.
  • Promotes Asset Circulation: Unlike Proof of Stake, where validators lock up their assets, PoI encourages the free movement of assets within the network.
  • Encourages Active Participation: PoI rewards users for more than just staking; it also considers how actively each miner engages in network transactions in frequency and volume.


  • Biased Toward Wealthy Participants: The algorithm favors those who can afford frequent, high-volume transactions, potentially sidelining smaller players.
  • Limited Incentives: Because the computational power required to mine blocks is relatively low, the rewards for validators are also modest, which may not be appealing for those running nodes as a business.


NEM blockchain introduced the Proof of Importance consensus algorithm.


The Future is Fluid

Blockchain consensus mechanisms are far from static. These foundational algorithms are pivotal in determining a network’s resilience, inclusivity, and long-term viability.

While we’ve explored some key consensus models, it’s vital to remember that this field is constantly evolving. Developers are ceaselessly experimenting, combining the best features of existing algorithms to engineer entirely new protocols. These emergent mechanisms have unique pros and cons, which must be evaluated within the network’s specific objectives.

So, as the blockchain sector continues to mature, the mechanisms that keep these decentralized networks secure and functional will also evolve.


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