Web3 Before Solana - 4

Everything you need to know before learning Solana (part 4)

Hey everyone ~ If you’ve made it to Part 4, we’re now stepping into one of the most crucial areas of Web3 where we finally understand how everything actually works under the hood. By now, you already have a solid grasp of the basics we covered in Parts 1, 2, and 3:
Blockchain, hashing, Merkle trees, cryptography...etc etc

In our last part, we saw how cryptography acts as the unbreakable shield for your digital money and identity. But how do thousands of computers around the world, none of whom fully trust each other, agree on what information to add to the blockchain? How do they ensure no one cheats or messes up the shared record? That's where Consensus Mechanisms come in.

Honestly, when I first read about Consensus Mechanisms, I didn’t understand a single word.
It literally made me want to bang my head against the wall. In fact, before even getting to the actual coding part of dApps, I seriously thought of giving up on Web3. Not because it was that hard but because I didn’t have the patience. I was rushing through everything without giving it the time it deserved. But after taking a proper deep dive, I can now say that Consensus Mechanisms have become one of my favorite concepts in Web3. If you're a beginner like I was don’t worry, you’ll get there too. Gradually, it all clicks.

So let’s begin Part 4.

Disclaimer - This part is going to be long. Take your time with it. Be patient. Put in the effort. Will be worth it

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What in the world is Consensus Mechanisms ???

In simple words Just like we have courts and a constitution to follow certain rules, blockchains use consensus mechanisms to stay in sync, stay secure, and stay fair. No one person controls the outcome the system itself, through code and logic, ensures everyone agrees on one final truth. As simple as that..

A consensus mechanism is simply a set of rules that helps all the computers in a blockchain network agree on the correct information. It helps them decide which transactions are valid, what new information should be added next, and ultimately, what the single, true version of the blockchain's history is. Without these rules, a decentralized system would fall apart, as everyone would have their own version of the truth. These rules are essential to prevent problems like someone spending the same digital money twice, and they keep the entire network secure without needing a central boss.

Definition of Consensus Mechanisms : A set of rules and protocols that allow all participants in a decentralized network to reach a collective agreement (consensus) on the state of the shared ledger.

So why is this actually important ??
→ Prevents Cheating: It stops actions like "double-spending" (using the same digital money twice).

→ Ensures Security: It protects the network from malicious attacks by making it computationally or economically too expensive to alter the blockchain's history.

→ Maintains Integrity: It guarantees that every node, despite being independent, always arrives at the same shared and verifiable version of truth.

So lets understand what all mechanisms exist in blockchain

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1. Proof of Work (PoW) – Used by Bitcoin ( You can skip to PoS after reading 1st para)

Proof of Work, or PoW, is the first consensus mechanism ever used in blockchain most famously by Bitcoin. Its core idea is simple but powerful thousands of computers around the world, called miners, compete to solve a very difficult mathematical puzzle. The one that solves it first gets to add the next block of transactions to the blockchain and earn a reward. This process ensures that block creation isn’t free or easy it takes real effort, energy, and resources. That’s why it’s called “Proof of Work.”
Also we will touch this topic in a part where we discuss disadvantages of blockchain.

Note → You can skip to the next part — you don’t need to know everything below to move forward. But if you're curious about how things work under the hood, feel free to dive in. Totally up to you.

Here’s how the process works behind the scenes. A miner collects a batch of unconfirmed transactions and starts assembling a block. Along with the transaction data, they include a timestamp, the hash of the previous block, and a special number called a nonce (a random value they can change). Then begins the real challenge: they take all that block data and feed it into a cryptographic hash function (like SHA-256 in Bitcoin), again and again, trying to get a hash output that’s lower than a specific target value set by the network. Usually, this means the resulting hash must start with a certain number of zeroes. There’s no shortcut to this it’s a pure guessing game, trying different nonces billions of times per second until a valid one is found.

Once a miner finally finds a valid hash, they immediately broadcast the completed block to the rest of the network. The other nodes quickly verify whether the hash meets the required condition and whether all the included transactions are valid. This part is easy and fast verifying the solution takes almost no effort, unlike finding it. If the block is valid, the network accepts it, and miners begin working on the next block. This process keeps repeating endlessly, one block at a time.

One of the most brilliant features of PoW is difficulty adjustment. The blockchain doesn’t want blocks to be created too quickly or too slowly, so it has a built-in system that automatically adjusts the puzzle’s difficulty over time. For example, Bitcoin targets one block every 10 minutes. If blocks are being found faster (because more miners or better machines have joined), the network increases the difficulty by lowering the target value. If blocks are found too slowly (due to fewer miners), it decreases the difficulty. This self-regulating mechanism ensures a stable and predictable block creation rate, no matter how the network grows.

Another critical concept in PoW is how the system resolves conflicts when two blocks are found at nearly the same time a situation known as a fork. In these cases, the network temporarily has two valid versions of the chain. But the nodes don’t panic they simply wait and keep mining. Whichever chain gets extended further (i.e., whichever one accumulates more Proof of Work by adding more blocks) becomes the official chain. The other, shorter one is discarded, and any transactions in it go back into the pool to be retried. This rule is called the Longest Chain Rule and is essential to maintaining a single version of truth across the network.

Security in PoW comes from its costliness. To attack the network say, by double-spending or censoring transactions an attacker would need to control more than 50% of the network’s total computational power. This is called a 51% attack. But in massive networks like Bitcoin, the hardware, electricity, and coordination needed to pull this off is so extreme that it's practically impossible. That’s what makes PoW incredibly secure and resistant to tampering.

However, all this security comes with trade-offs. Proof of Work is energy-intensive miners around the world consume vast amounts of electricity. It’s also relatively slow because the block times are fixed (e.g., 10 minutes in Bitcoin), and the network can only handle a limited number of transactions per block. Over time, this has led to the rise of newer consensus mechanisms that aim to improve on PoW’s limitations.

Still, Proof of Work remains the gold standard for blockchain security proven, time-tested, and foundational to how decentralized trust was first achieved in the world of crypto.

Thats a lot of confusion right never mind lets now understand crucial parts

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2 Proof of Stake (PoS): The Economic Way to Secure the Blockchain

In simple words people who lock up some of their own coins (called staking) get the chance to validate the next block.

More coins = more chance to be chosen.

Proof of Stake is a method blockchains use to decide who gets to add the next block of transactions. It replaces the energy-heavy competition used in Proof of Work with a system based on staking coins.

It passes through 5 important stages

Staking | Validator Selection | Block Proposal | Slashing

Lets deep dive how it actually works

Proof of Stake (PoS) is a energy-efficient way for blockchains to reach consensus without relying on massive computing power. Instead of solving mathematical puzzles like in Proof of Work (PoW), PoS works through economic commitment. Participants called validators are chosen to propose and validate blocks based on how much of the network’s cryptocurrency they are willing to “stake” (lock up) as collateral.

The more coins a validator stakes, the higher their chances of being randomly selected to create the next block. Once selected, the validator collects pending transactions, creates a new block, signs it using their private key, and broadcasts it to the network. Other validators then attest to its validity by voting cryptographically. If two-thirds or more validators agree, the block is officially added to the chain.

How Ethereum Uses Proof of Stake

Ethereum transitioned to Proof of Stake with its upgrade known as The Merge. In this system, anyone who wants to become a validator must lock up (stake) 32 ETH into a smart contract on the Ethereum network. Once registered, the network randomly selects one validator at a time to propose a new block. Other validators are then chosen to attest (vote) on the validity of the proposed block. If a supermajority (usually two-thirds) agree that the block is valid, it is added to the blockchain. This system reduces energy use drastically compared to Proof of Work. It also provides finality, meaning once a block is finalized through Ethereum’s Beacon Chain, it becomes mathematically irreversible. Ethereum's PoS relies on strong cryptographic rules and financial incentives to maintain security, scalability, and fairness.

• Finality Time: Around 12 minutes using a system called "epoch justification and finalization".

• Throughput: Ethereum currently supports around 15–30 transactions per second (TPS), but this is being improved through Layer 2 scaling (like Arbitrum, Optimism) and sharding in future updates.

To maintain trust and security, PoS includes a strong penalty mechanism called slashing. If a validator misbehaves by proposing invalid blocks, staying offline too long, or creating conflicting blocks they risk being slashed. This means losing a portion or even all of their staked cryptocurrency. The threat of slashing ensures validators act honestly and helps prevent problems like the “nothing at stake” issue, where validators could otherwise support multiple versions of the chain without consequences.

A widely used variation of PoS is called Delegated Proof of Stake (DPoS). Instead of everyone staking directly, token holders vote to elect a smaller group of trusted delegates (also known as block producers). These elected delegates are then responsible for validating and producing blocks. DPoS allows much faster transactions and scalability, since only a few nodes need to reach consensus. However, it introduces centralization risks, as a smaller number of participants hold the decision-making power. This makes active governance and community voting very important in DPoS systems to avoid manipulation or mismanagement.

In DPoS, instead of everyone validating, users vote for a smaller group of delegates (or block producers). These elected delegates validate and propose blocks, which increases speed and scalability.

• Faster TPS: Some DPoS chains like EOS can process up to 4000+ TPS.

• Trade-off: More centralization a few powerful delegates can control the network if voters are passive.

Compared to PoW, PoS is significantly more energy-efficient, enables faster transaction processing, and requires no expensive mining hardware. Still, it's not free from challenges like the potential for stake centralization (where wealthy validators dominate) or rare but dangerous long-range attacks.

Many PoS networks, including Ethereum, use additional protocol safeguards to manage these risks. Despite its trade-offs, PoS is considered a major leap forward in blockchain consensus design offering a strong balance of security, sustainability, and scalability for the future of decentralized systems.

PoS vs PoW (ChatGpt help)

Okay, that’s already a lot of head-banging moments but just a few topics left, we’ll wrap up soon!

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3 Proof of History (PoH) – Solana’s Secret

In simple words Solana doesn’t just agree on the answer it also agrees on time. PoH adds a special clock/timestamp to every transaction. This makes everything faster, as validators don’t need to wait for others to agree.

Proof of History (PoH) is a unique innovation used by Solana that works alongside Proof of Stake, not as a standalone consensus mechanism. It acts like a cryptographic clock that helps all validators agree on the order of transactions without needing to communicate in real time. Instead of waiting for validators to talk and reach agreement on when each transaction happened, PoH already gives them a verified, tamper-proof timeline.

Lets deep dive how this actually works

Solana’s lead validator performs a continuous hashing process where each hash is based on the one before it. This creates a chain of hashes that act like timestamps. When a transaction or event happens, it’s inserted into this ongoing hash stream. The output at that exact moment becomes a verifiable proof that the event happened at that specific point in time. Since every hash depends on the previous one, anyone can go back and confirm how much time has passed between two events by redoing that part of the hash sequence. (interesting right!)

This mechanism allows Solana to sort and timestamp transactions before they even reach the consensus layer. Because the order is already locked in by PoH, validators don't have to waste time discussing or verifying the sequence they just follow it. This dramatically reduces communication overhead and allows Solana to process transactions in parallel using its Sealevel runtime.

As a result, the network can achieve extremely high speed around 65,000+ transactions per second and very low fees, usually under $0.01. Finality (when a transaction is permanently confirmed) happens in less than a second. PoH is what enables this level of performance by solving one of the biggest challenges in blockchain agreeing on time and order in a decentralized way.

However, here’s a thing PoH is also more complex than traditional systems and not easy to implement elsewhere. It’s custom-built for Solana’s architecture, making it powerful but less portable to other chains.

Still, when combined with PoS, it gives Solana a huge advantage in terms of speed, scalability, and cost-efficiency especially compared to older models like PoW or standard PoS chains.

And yeah thats alot of understanding but even your are still confused here’s a brief short breakdown

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Breif Breakdown :

Proof of Work (PoW) →

Nodes (called miners) solve complex mathematical problems. The first one to solve it adds the next block to the blockchain. Miners compete to find a correct hash (a solution). This takes time and energy (electricity). Once found, the new block is added, and the miner gets rewarded.

→ Usage: Bitcoin, older blockchains.

→ Pros: Very secure, simple design.

→ Cons: Very slow, consumes huge electricity, expensive to run.

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Proof of Stake (PoS) →

Nodes are selected to add the next block based on how many coins they have locked (staked) in the system. If you stake more coins, you have a higher chance of being selected to validate transactions and add blocks. If you cheat, your stake is slashed (burned).

→ Usage: Ethereum (after merge), Cardano, many newer chains.

→ Pros: Energy-efficient, faster, scalable.

→ Cons: People with more coins have more power. Risk of centralization.

Delegated Proof of Stake (DPoS) →

A small group of validators are elected by token holders to validate transactions on their behalf. Users vote for delegates (validators). Those few validators produce blocks and confirm transactions. Voting power depends on how many tokens you hold.

→ Usage: EOS, TRON.

→ Pros: Very fast, highly scalable.

→ Cons: More centralized (only a few validators). If voters don’t participate, system can become weak.

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Proof of History (PoH) (Solana-specific) →

A system that adds a secure timestamp to every transaction so that validators already know the order of events. A cryptographic clock is used to order all transactions before consensus. That way, validators don’t wait to agree on time—they already trust the timeline and process transactions in parallel.

→ Usage: Solana

→ Pros: Extremely fast (up to 65,000+ TPS), highly efficient.

→ Cons: Complex to understand and implement. Not widely adopted outside Solana.

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Key Differences Table (ChatGPT help)

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Byzantine Fault Tolerance (BFT): The Core Problem Consensus Solves

Okay, but why all these mechanisms in the first place?

At the core of every consensus mechanism whether it's Proof of Work, Proof of Stake, or Solana’s Proof of History + PoS combo lies one core challenge: achieving Byzantine Fault Tolerance (BFT). In simple terms, BFT is a system’s ability to keep functioning correctly and reach agreement, even if some nodes are faulty, crash, or act maliciously by sending wrong information or trying to cheat the system.

In decentralized networks, there's no central controller to decide what’s true. So, the real problem is how can independent nodes trust and agree on the same data, especially when some might be unreliable or trying to attack? This is known in computer science as the Byzantine Generals’ Problem how to reach consensus despite miscommunication or betrayal.

Here’s how each major mechanism addresses it:

→ Proof of Work (PoW): solves this by making cheating extremely expensive. To mislead the network, an attacker would need over 50% of the total computational power nearly impossible for big chains like Bitcoin.

→ Proof of Stake (PoS) handles it economically: validators have to lock in coins as a security deposit. If they act dishonestly, they get slashed losing their stake, which creates strong incentive to stay honest.

→ Solana’s combo of Proof of History + PoS makes the process even faster and more scalable by solving one extra bottleneck time. PoH provides a verifiable order of events upfront, so validators don’t have to waste time arguing over who said what and when they can just verify and move on.

So whether it’s computation, money, or time every consensus model is a unique way to solve the same core challenge getting a decentralized system to agree, securely, even when not everyone can be trusted.

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Conclusion on Consensus mechanisms

Consensus mechanisms are not just abstract concepts they are the highly engineered algorithms that make decentralized systems functional and secure. They are the absolute core of how decentralized blockchains function. They provide the strict rules that allow thousands of independent computers to work together and maintain a single, consistent, and secure shared record without any central boss. They define exactly how new information is added, how its validity is confirmed, and how the entire network resolves any disagreements. Without these crucial agreement protocols, a decentralized blockchain simply couldn't exist reliably.

→ They ensure a global network of strangers can agree on one shared, unchangeable truth.

→ They let blockchains stay secure, fair, and censorship-resistant, no matter how big the network or how untrusted the participants.

→ Whether it's Proof of Work, Proof of Stake, or Proof of History, understanding this really really imp

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Final thoughts

Okay, that’s a lot to digest especially if you’re a beginner. This topic is definitely on the heavier side, and yeah, the post is very long too. So I really recommend reading it at least 2 to 3 times slowly. Don’t rush it. Let it sink in. Then try exploring on your own, ask GPT questions, look up examples, test your understanding. That’s when things will start clicking.

And yeah just being honest, this blog is written 80 percent purely from scratch by me. I have all the notes from these past days weeks , and the structure, flow, everything is from my own learning and effort. I compiled all the key points I’ve been learning over time, added what I understood, and structured it in my own way.

The thoughts, breakdowns, and curation because I feel only a learner can truly understand the perspective of another learner. I know learning all these concepts from scratch isn’t easy at all. I’ve been there, still roaming here.

Around 20 percent is AI help, so credit also goes to AI. The remaining 80 percent comes from deep research and learning from different resources, docs, and reading.

This blog is a mix of hardwork , everything I’ve learned so far…

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With that said yeah Alright hope you understand this
And yeah, I know… this was another long one (deal with it).
But I’d rather over-explain than leave you half-cooked in Web3.

RESOURCES
https://ethereum.org/en/developers/docs/consensus-mechanisms/pos/
Types Of Consensus Mechanisms In Blockchain - Hacken ( HIGHLY RECOMMENDED)
Proof of History: How Solana brings time to crypto | Solana (just get an overview)
Byzantine fault - Wikipedia

If it helped you understand things in a way that saves you from banging your head on the wall like I did mission complete. Welcome to the world of Web3 and blockchain with me. The journey starts here. Keep learning keep coding keep reading..

It doesn’t stop here ~ Maha ( Haha just kidding any doubt just a dm away)

Thankyou ~ ciaa in next part with some core concepts and diff blockchains etc etc.

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