Field notes on unspent outputs
Your balance is a fleet of boats, each tied to its own mooring.
Bitcoin does not keep one tidy number for you. It keeps outputs: discrete amounts, each one waiting untouched until someone uses it, once, to pay for something. Moorline is a reading room for that model, written slowly for people who like to know where every boat is tied.
The manifesto
Most of us meet money as a single figure. An app shows a balance, the figure rises when something arrives and falls when something leaves, and that is the whole story we are invited to read. Underneath, the Bitcoin ledger tells a different one. It keeps no account balance at all. It keeps a set of unspent transaction outputs, or UTXOs, and your balance is only the sum of the ones your keys can unlock.
That difference is not a technicality. It shapes what a payment is, why change exists, why fees are simply a gap, and why every node on the network can check the same record and reach the same answer. Once the model is clear, much of the rest of Bitcoin becomes easier to reason about.
So we hold to a plain image. Every output is a boat on a mooring. It sits there, counted, and it can be cast off exactly once. When it leaves the dock, it leaves whole. Whatever it does not need goes back to you as a new boat on a new mooring. Nothing in the harbor is ever split in half and quietly patched.
What Moorline is
Moorline is an independent explainer. We are not an exchange, a broker, a wallet, or an adviser, and nothing here is a recommendation about what to buy, hold, send, or sell. We write explanations, keep a glossary of the working vocabulary, and offer one interactive model: the payment dial, which shows how a payment picks outputs and returns the change.
Everything on this site is static. It loads from its own files, asks nothing of a server, and shows the same information to every visitor.
Who it is for
- Developers who have read the protocol notes but have never watched a change output fall out of a transaction.
- Students and writers who need the idea in plain words before the vocabulary arrives.
- Curious owners who opened a wallet, noticed that the balance was built from pieces, and wanted to know why.
How we write
Short sentences where the idea is hard. Longer ones only where the idea needs room to breathe. We define a term when it first appears and again in the glossary. We do not pretend the model is simpler than it is, and we do not dress it up as more mysterious than it is.
- Name the thing before using it.
- Show the mechanism before the consequence.
- Say what is not known, and say what this site is not.
Begin here
Two doors open from the harbor. The mooring guide walks through inputs, outputs, change, fees and coin selection in the order you will need them. The payment dial lets you set a payment size and watch the berths respond.