How the network works
Crypto Dispensers | Bitcoin learning path
AI-generated narration. Original diagrams; fictional examples.
Reviewed October 23, 2026.

Which payment should count?
Imagine Maya has one spendable Bitcoin amount. She signs two conflicting transactions using it. One pays Leo, and the other pays Noor. A transaction is a proposed record of spending. Both payments can't spend the same funds on the accepted history. A signature can show permission to spend, but it can't by itself choose which payment counts. Bitcoin needs both spending rules and an agreed order. A bank uses its own records. Let's see how a public network approaches the problem.

A key authorizes spending
A private key is secret computer information used to authorize spending. A wallet prepares a transaction and uses the required keys to make a digital signature. Other computers can check that signature without learning the secret key. This proves something about authorization. It doesn't prove a payment request is honest or settle the order of conflicting payments. Keep permission, ordering and the recipient's honesty as separate questions.

Follow a fictional payment
Suppose Maya controls an unspent amount of one hundred thousand sats. She wants to pay Leo thirty thousand. Her transaction creates thirty thousand sats for Leo and sixty-nine thousand sats of change for her. The remaining one thousand sats is the network fee. One hundred thousand in, ninety-nine thousand in outputs, and one thousand as the fee. An output assigns an amount under spending conditions. These amounts are invented arithmetic, not a recommended fee.

Nodes check the spending rules
A node is a computer running Bitcoin software. A full node checks transactions and proposed blocks against the rules it enforces. It checks spending authorization, the amounts and whether an earlier amount has already been spent in the history it accepts. If a conflicting payment spends Maya's original amount first on the accepted chain, she can't spend it again there. Her wallet doesn't send a file containing coins, and its signature doesn't publish her private key.

Miners propose blocks
A block groups transactions together. Miners repeatedly calculate hashes, which are fingerprints derived from block data, until they find a result that meets the required target. This search is called proof of work. Finding that result takes computing resources. Other nodes can check it quickly and still check the block's other rules. Mining work helps order valid history. It doesn't make an invalid payment or an excessive reward acceptable.

Blocks connect to earlier blocks
Accepted blocks form the blockchain, a linked transaction history. Each block refers to an earlier block through its hash. Changing earlier information changes the fingerprints that later blocks refer to. An attacker can't make an altered history acceptable simply by recalculating those links. It must contain valid transactions and sufficient accumulated proof of work. These requirements explain why the record involves more than a list of payments.

What if two blocks arrive together?
Two miners can find valid blocks close together. Some nodes may hear about one first, while others hear about the other. For a time, there can be competing valid histories. Nodes follow the valid chain with the most accumulated proof of work. Later blocks can extend one branch until it becomes the history they follow. A payment in the other branch may become unconfirmed again or conflict with spending on the accepted branch.

Why confirmations help
Broadcast means a transaction has been shared with other computers. Its first confirmation means inclusion in a block on the current chain. Later blocks add confirmations and generally reduce the chance of reversal through a competing chain. This isn't one vote per computer. Creating thousands of computer identities doesn't create thousands of votes over the history. Proof of work gives the ordering process a cost, while full nodes keep checking validity independently.

Why use electricity?
Proof of work makes competing to propose blocks costly, while checking the result is quick. Its search serves the ordering of Bitcoin's history. It isn't solving medical research problems or other outside calculations. Electricity and equipment are real costs. Whether the system's benefits justify them is a further question people disagree about. Energy consumption and emissions also aren't identical measures. The deeper mining guide explains these distinctions without promising every attack is impossible.

Where trust still remains
You don't have to run mining equipment or a node to learn about Bitcoin. Most people still rely on software, devices and services. If a provider holds the keys, its security and withdrawal practices matter too. Self-custody means managing your own spending keys and recovery information. It can reduce reliance on a custodian while increasing your responsibilities. The network can check rules. It can't decide whether this is the recipient or payment you intended.

Does expensive work excuse a bad block?
Now try this: a miner finds valid proof of work, but its block claims more new Bitcoin than the rules permit. Must a full node accept it because the work was expensive? No. It checks the other rules and rejects the block. Choosing between valid histories is different from accepting an invalid one. Return to stage two for its understanding check, then explore how the supply rules fit into the miner's reward.

Continue: https://www.cryptodispensers.com/learn#lp-network

Primary references
https://bitcoin.org/bitcoin.pdf
https://developer.bitcoin.org/devguide/block_chain.html