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The Bitcoin System
Bitcoin is a set of rules for digital value.
The rules are public and predictable.
This site explains the layers in simple English.
Short sentences. Direct definitions. Layer-by-layer learning.
What is money?
Money is a tool for trade.
It helps people exchange work and goods.
It also helps people save value for later.
Good money is easy to verify.
It is hard to fake.
It is accepted by many people.
Store of value
This means money can keep value over time.
It helps planning for the future.
Medium of exchange
This means money can be used for payment.
It reduces the need for barter.
Unit of account
This means money is used for prices and measurement.
It helps compare different goods.
Why Bitcoin exists
Digital payments usually need a trusted middleman.
A middleman is a company that can block, reverse, or limit payments.
Bitcoin reduces the need to trust one company.
It does this with shared rules and shared verification.
The core idea
Bitcoin is decentralized.
Decentralized means no single party controls the system.
Bitcoin has scarcity.
Scarcity means the supply follows strict rules.
Bitcoin follows rules that anyone can check.
Rules are enforced by software run by many people.
Open verification
Anyone can run a node.
A node is software that checks the rules.
Predictable supply
New coins follow a schedule.
The schedule is part of the protocol rules.
Neutral settlement
Payments are accepted by rules, not by permission.
This is called permissionless validation.
The layer model
Bitcoin can be explained as layers.
A layer is a system built on top of another system.
The base layer is the mainchain.
Lightning is built on Bitcoin.
Cashu is built on Lightning.
Mainchain
The global ledger.
It is slow by design but very hard to change.
Lightning
A payment network using Bitcoin as the anchor.
It moves value quickly between users.
Cashu
Ecash tokens issued by a mint on Lightning.
It can improve privacy for small payments.
Mainchain defines the core rules and settlement.
Lightning moves payments without writing every one on-chain.
Cashu can hide payment details from the mint in many cases.
How the layers work together
Think of layers as different tools.
Each tool has a purpose.
You choose based on your needs.
Mainchain is best for strong settlement.
Lightning is best for speed.
Cashu is best for small private payments with a clear trust trade-off.
Settle on Mainchain
Settlement means recording a final result.
Mainchain settlement is slow but very robust.
Pay on Lightning
Lightning uses channels.
Channels let people update balances without on-chain writes.
Hold ecash in Cashu
Cashu uses a mint.
A mint issues tokens and must be trusted to redeem them.
FAQ
Is Bitcoin anonymous?
Bitcoin is not fully anonymous.
Mainchain payments are public.
Privacy depends on how you use the system.
Why not put all payments on the mainchain?
The mainchain has limited block space.
Limited means it cannot fit unlimited activity.
Layers help scale by moving many payments off-chain.
Are layers “less real” than Bitcoin?
Layers are real systems, but they have different trust and risk.
The mainchain is the base settlement layer.
Higher layers can add speed or privacy with trade-offs.
Start with the base layer.
Then learn how Lightning builds on it.
Then learn what Cashu adds on top.
Next steps
Each page is short and focused.
You can read them in any order.
Many people start with the mainchain.
Mainchain (Layer 1)
Learn blocks, transactions, mining, and settlement.
This is the foundation.
Lightning (Layer 2)
Learn channels, routing, and liquidity.
This is for fast everyday payments.
Cashu (Ecash)
Learn ecash tokens and mints.
This is for privacy with a clear trust model.