Mining Lab · Coinovo Academy · How the network really works
Nodes, mempool, forks
It is not miners who decide what counts but the nodes: computers that check every rule and reject invalid blocks. A miner who breaks the rules works for nothing.
Miners propose, nodes decide.
Your wallet signs and sends the transaction to its nodes. They check and pass it on until it is known across the network. There it waits in the mempool for a miner. Each of those steps takes seconds; the waiting only starts afterwards.
One confirmation means your payment sits in a block. Every further block on top makes reversing it more expensive. Six confirmations are customary for large amounts; for small ones, one is often enough.
If two miners find a block almost simultaneously, the network briefly has two ends. The dispute resolves itself: the chain that gets built on wins. The other block is orphaned, and its payments go back into the mempool.
That is why a single confirmation is not yet certainty.
A block is not limited in bytes but in weight units. From that follows the size in virtual bytes you pay fees by. Signatures weigh less than the rest of the content, which makes certain address formats cheaper.
If a transaction is marked replaceable, it can be replaced by a second one with a higher fee for as long as it is unconfirmed. Anyone who budgeted too tightly does not have to wait. Recipients should therefore never treat unconfirmed payments as final.
Unconfirmed means: still changeable.
Whoever checks for themselves has to believe nobody. Without your own node you rely on someone else telling you the truth, usually your wallet's provider. A node is also the only way to send your payments without a third party keeping a record.
A soft fork tightens rules, and old nodes keep accepting the new blocks. A hard fork loosens them; whoever does not go along ends up on a different chain. That is why hard forks are rare and contested: they require practically everyone to join in.
With more than half the computing power, your own payments could be reversed and others shut out. What would not be possible is moving other people's coins or inventing new ones: the nodes check that, and computing power changes nothing about it.
A majority means influence over the order, not over the rules.
The question is rarely "could it be done?" and almost always "what does it cost and what does it bring?".
To muster the majority of computing power today you would need more machines than the entire industry builds in a year, plus the grid connections and the power for them. The purchase runs into tens of billions, the electricity into millions a day.
And what would it bring? You could reverse your own payments and shut others out. You could NOT move other people's coins, because that would need their keys, and not invent new coins, because the nodes check that.
So the gain from an attack is limited to what you yourself spent shortly beforehand, and the attack would crash the price of the very currency the attacker holds their machines and loot in. That is the real protection: not impossibility but unprofitability.
For Bitcoin the sum is clear-cut. For smaller networks of the same design it is not: there computing power can be rented by the hour, and a day sometimes costs five figures.
That has happened several times. What was attacked was not users but exchanges: deposit coins, trade them, withdraw something else, then reverse the deposit.
From that follows a practical rule for anyone dealing with smaller networks: the number of confirmations you wait for has to match the size of the network. Six confirmations mean something entirely different on Bitcoin than on a chain with a thousandth of the computing power.
Lightning moves many small payments into channels between two parties and writes only the opening and closing into the chain. That makes payments instant and almost free, at the price of constant availability and tied-up funds. It does not replace the chain, it relieves it.
Tasks, shifts and the daily hunt, plus an account that shows what has added up.
Opens straight away. No account, nothing to install.