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Consensus (Input, Not Memory)

Consensus isn't about "memory storage." It's about agreeing on the order of inputs.

Consensus orders inputs
Agreement is about transaction order, not about storing memory.

Learning Objective

  • Define consensus as ordering transactions
  • Explain why RPC concentration is a decentralization risk
  • Recognize validator, RPC, and light node roles

What to Expect

  • Consensus explained as input ordering, not data storage
  • Node roles and why they matter
  • A stepper simulation of ordering and finalization

Consensus Is About Input

Blockchains reach agreement on transaction order. The ledger is the result of that ordered input, not the thing that consensus directly "stores."

Node Roles

Validator

Participates in consensus and produces blocks.

RPC Node

Provides read/write access for clients (wallets/apps).

Light Node

Keeps minimal data and relies on others for full history.

Decentralization Risk

If most users rely on a few RPC providers, the system becomes effectively centralized even with many validators.

Ordering Simulation (Interactive)

1. Collect Inputs

Transactions arrive from clients.

2. Propose Order

Leader suggests an ordering.

3. Vote

Validators verify and vote.

4. Finalize

Ordered inputs become history.

Checkpoint Quiz