Put the Bitcoin machine together.

Follow the evidence.

A wallet can display public information without controlling the key. A spending wallet constructs a transaction, accounts for its inputs and outputs, and signs the required data. A custodian may instead do that on a customer’s behalf.

Nodes check whether the payment follows their rules. A local mempool can hold it before a miner includes it. Inclusion in a valid block adds a confirmation; subsequent work increases confidence in that history.

Inside the block, transactions contribute to a Merkle root. The header commits to that root and the previous header’s hash. Linking pages exposes edits; proof of work makes competing valid histories costly to produce.

Each piece has a limit. A signature does not establish wise intent. A hash does not prove an outside fact. Work does not make an invalid reward valid. And more confirmations do not create an absolute guarantee.

Then locate the power.

Custody asks who can authorize spending. Decentralization asks where meaningful control sits. Consensus combines validity rules and history selection; governance concerns changing the arrangement.

Bitcoin’s subsidy schedule is one of those validity rules. It bounds issuance under the current software. It does not guarantee demand, protect a recovery phrase or answer the environmental question.

The model is useful when it helps you diagnose a new situation. If a withdrawal freezes, look at custody. If a candidate block invents value, look at validation. If two recent valid histories compete, look at accumulated work. Different problems need different explanations.

Work security also has costs: hashing resources, environmental effects and an evolving subsidy-and-fee budget. Ask about those costs separately from whether a particular payment is valid.

The idea to keep

You do not need to memorize every acronym. You need to know which evidence establishes permission, validity, ordering and control—and where that evidence stops.