Mining / Block Proposals – How a Block Gets Chosen
Intent: Explain how miners or validators compete or cooperate to add the next block, and how incentives keep the network honest.
The Core Question
If anyone can participate in a blockchain network, who decides which block becomes the next official block?
That decision is the heart of mining (in Proof of Work) and block proposal (in Proof of Stake). These mechanisms answer two critical problems at once:
- How do we choose one block out of many candidates?
- How do we motivate participants to follow the rules instead of cheating?
Let’s break it down.
Two Ways to Propose a Block
Modern blockchains typically follow one of two models:
- Mining (Proof of Work – PoW)
- Validation / Block Proposal (Proof of Stake – PoS)
Different mechanics—same goal: secure block selection.
Mining (Proof of Work)
What Is Mining?
Mining is a competitive process where participants (miners) race to solve a cryptographic puzzle.
- Miners collect valid transactions from the mempool
- They bundle them into a candidate block
- They repeatedly hash the block header, trying to find a valid result
The first miner to succeed earns the right to publish the block.
Why the Puzzle Matters
The puzzle is designed to be:
- Hard to solve (requires computation)
- Easy to verify (any node can instantly check it)
This asymmetry makes cheating extremely expensive.
Incentives for Miners
Why would anyone spend electricity and hardware on this?
Miners are rewarded with:
- Block reward (newly minted coins)
- Transaction fees from included transactions
If a miner cheats:
- The network rejects the block
- The miner earns nothing
- Energy cost is wasted
Honesty is the most profitable strategy.
Block Proposals (Proof of Stake)
What Changes in PoS?
Instead of burning electricity, Proof of Stake relies on economic stake.
Participants (validators) lock up tokens as collateral.
- No race
- No heavy computation
- No massive energy usage
Instead, the protocol selects a validator to propose the next block.
How Is a Validator Chosen?
Selection depends on factors like:
- Amount of stake locked
- Randomness
- Time since last proposal
- Protocol-specific rules
The goal is fairness and unpredictability.
Validator Incentives
Validators earn:
- Block rewards
- Transaction fees
But there’s a twist.
If a validator acts maliciously:
- Their stake can be slashed
- They lose real money
This makes attacks economically irrational.
From Proposal to Acceptance
Regardless of PoW or PoS, the flow looks like this:
- Candidate block is created
- Block is broadcast to the network
- Other nodes verify:
- Transactions
- Signatures
- Block rules
- If valid → block is accepted
- If invalid → block is rejected
Consensus ensures everyone agrees on the same history.
Why Incentives Are Everything
Blockchains don’t rely on trust—they rely on aligned incentives.
Good behavior:
- Gets rewarded
- Builds long-term profit
Bad behavior:
- Gets rejected
- Loses money or resources
This is game theory applied to networks.
Mining vs Block Proposals – Quick Comparison
| Feature | Proof of Work | Proof of Stake |
|---|---|---|
| Security Cost | Electricity | Locked capital |
| Block Creator | Fastest miner | Selected validator |
| Penalty for Cheating | Wasted energy | Slashed stake |
| Energy Use | High | Low |
| Entry Barrier | Hardware | Tokens |
Why This Matters
Block selection is what makes blockchains:
- Decentralized
- Tamper-resistant
- Economically secure
Without strong incentives, the system collapses.
With the right incentives, strangers across the world cooperate—without trusting each other.
Mental Model to Remember
Proof of Work: “Prove you burned resources.”
Proof of Stake: “Prove you have something to lose.”
Either way, the network chooses the block that’s backed by real economic cost.
Up Next
Next lesson naturally follows into:
Finality & Forks — What Happens When Blocks Compete
Where we’ll explore chain splits, reorgs, and how blockchains eventually settle on one truth.
