Academy School · Chapter 2 of 14
Blockchain Architecture
How blockchains work, how layers differ, and why design choices matter.
Chapter locked
Complete the previous chapter first.
Academy School builds each concept on the one before it. Return to the course overview to continue from your current chapter.
Return to Academy SchoolWhat a Blockchain Is
A blockchain is a shared ledger maintained by many independent nodes. Transactions are grouped into blocks, and each block links to the one before it, creating an ordered history that is difficult to rewrite quietly.
This structure is designed for public verification. Instead of relying on one database owner, participants can check the same record and compare results against the network’s rules.
- Shared ledger, not private database.
- Blocks link into an ordered history.
- Independent nodes verify the record.
A blockchain is a distributed system for keeping a shared history.
Consensus and State
Consensus is the process that lets a network agree on which history is valid. Different blockchains use different methods, but the goal is the same: maintain a single recognized state across many participants.
State is the current condition of the ledger, including balances, contract data, and other network records. Understanding state helps explain why blockchains are more than just payment rails.
- Consensus decides valid history.
- State is the ledger’s current condition.
- Different networks use different trust models.
Consensus keeps the network aligned on a single version of truth.
Monolithic vs Modular Design
Monolithic blockchains try to handle execution, settlement, and data availability in one system. They can be simpler to understand, but they may face tradeoffs in throughput and flexibility as demand grows.
Modular designs split responsibilities across layers. This can improve scaling and specialization, though it adds coordination complexity and requires careful trust analysis.
- Monolithic design keeps functions together.
- Modular design splits responsibilities.
- Each approach has tradeoffs.
Architecture is about balancing simplicity, scale, and trust.
Layer 1s and Layer 2s
Layer 1 is the base chain that provides settlement and security. Layer 2 systems sit above it and extend capacity, reduce friction, or add functionality while still depending on the base layer in important ways.
The right design depends on the job. Some applications need maximum base-layer simplicity; others need faster, cheaper interaction on top of a secure settlement layer.
- Layer 1 anchors security.
- Layer 2 extends capacity or functionality.
- Use case should drive design choice.
Layering lets a blockchain stay secure while becoming more useful.
Further reading