THE BITCOIN NETWORK
26,634 MACHINES AGREEING, WITH NOBODY IN CHARGE
Bitcoin is not a company, an app, or a place. It is tens of thousands of ordinary computers running the same rules and checking each other, all the time. There is no head office to raid, no server to unplug and nobody to phone. That is not a slogan. It is the reason it has not stopped once in 17.7 years.
- MACHINES KEEPING A COPY
- 26,634
- YEARS WITHOUT STOPPING
- 17.7
- BLOCKS THEY ALL AGREE ON
- 965,970
- GUESSES PER SECOND
- 931QUINTILLION
- HOW HARD IT IS NOW
- 127.5TRILLION
- MINUTES BETWEEN BLOCKS
- 10
WHAT THE NETWORK ACTUALLY IS
There is no Bitcoin server. When you send a payment, it does not go to a company. It goes to whichever machines your software happens to be connected to, and they pass it on to the machines they are connected to.
A few seconds later it is everywhere. Nobody routed it. Nobody approved it. Nobody could have stopped it.
Every one of those machines holds the same record, back to 2009, and checks every rule of it alone. They do not vote and they do not confer. They each apply the same rules to the same facts, so they land on the same answer.
That is the whole trick. Agreement without a meeting.
DECENTRALIZED IS NOT A MOOD
The word gets used to mean modern, or good, or ours. Here it means something you can check, and you check it by asking three plain questions.
Who could switch this off? For a bank, that is a name. For an app, a company. For Bitcoin you would have to name 26,634 machines in dozens of countries, most of which do not know each other, and get to all of them at once.
Who decides the rules? Nobody decides them. A rule holds because every machine throws away blocks that break it. Somebody who wants a different rule can write it, publish it and run it, and it changes nothing at all unless other people choose to run it too.
What would it cost to force a change anyway? That one has a number, and it is the next section.
WHAT IT WOULD COST TO ATTACK IT
The honest version, without the drama.
To rewrite recent history you would need more guessing power than everybody else put together. The network is making about 931 quintillion guesses every second. You would need to beat that, and keep beating it, with machines nobody sells in that quantity.
And it buys much less than people think. You could try to undo one of your own recent payments. You could not create coins out of nothing, take somebody else's coins, or raise the 21,000,000. Every machine checks those rules, and it would throw your blocks away however much electricity went into them.
The strongest part of it is boring. The more it is worth attacking, the more machines compete for the reward, and the more expensive attacking it becomes. It defends itself with the same thing that makes it valuable.
And it gets safer behind you as you wait. Undoing a payment means redoing every block built after it, faster than everyone else is building new ones. Six blocks deep, that is already a losing race.
WHY IT IS DIFFERENT FROM WHAT CAME BEFORE
Every payment system before this one had a middle. Somebody kept the list of who owns what, and everybody else asked them. It works, and it works well, right up to the day you disagree with the person holding the list.
Bitcoin got rid of the middle by making the list public and making the checking everybody's job.
The trade is real and worth saying out loud. Nobody can freeze your money, and nobody can get it back for you either. That is one property seen from two sides, not a feature and a flaw.
None of it asks you to trust the people who built it. Not the miners, not the people writing the software, not this website. Every number on this page came off the network and anyone can go and read it for themselves.
QUESTIONS
Who controls the Bitcoin network?
Nobody, and that is not a figure of speech. The rules are applied by every machine separately. There is no company, no board and no key that overrides them. A change only happens if the people running the software decide to run different software.
How does the Bitcoin network work?
Tens of thousands of computers each hold the whole record and check every rule of it themselves. Payments are passed from machine to machine until everyone has them. About every 10 minutes, one miner wins the right to add the next block, and every machine checks that block before keeping it.
Why is Bitcoin called decentralized?
Because no single place holds it and no single party decides it. The word is worth checking rather than believing, and it checks in three questions: who could switch it off, who could change a rule, and what either would cost. Here all three come out as nobody, or as a bill nobody can pay.
Can the Bitcoin network be shut down?
There is nothing to shut down in one place. A country can make it illegal, and some have, which pushes machines elsewhere rather than removing them. The network has kept producing blocks through every such attempt so far.
What is a 51% attack?
It means one party controlling more guessing power than everyone else combined. It would let them try to undo their own recent payments. It would not let them create coins, spend coins they do not own, or change the rules, because every machine checks those separately.
Has the Bitcoin network ever gone down?
It has never stopped producing blocks since 2009. It has had two serious incidents, in 2010 and in 2013, both caused by bugs in the software rather than by an attack, and both sorted out within hours by people running fixed software. Saying it has never had a bad day would be a sales pitch.
How many computers run the Bitcoin network?
26,634 can be reached from outside right now, and that is a floor rather than a total: a machine that does not accept incoming connections does the same work and cannot be counted by anybody.
SEE IT RUNNING
The tour ends on this. It steps back from the whole machine and says it out loud: it is not one machine, it is tens of thousands of them, in every country, checking each other tonight.
WHAT TO READ NEXT
- NODESthe machines doing the checking, and what running one gives you
- MININGwhere the guessing power comes from
- BLOCKCHAINthe record they all hold the same copy of
SMALL PRINT
The machine count comes from a public crawler and is a floor, not a total. The guessing power is an estimate worked out from how fast blocks have been arriving, which is the only way anybody can measure it: nobody reports their machines to anyone. This page gives no financial advice and names no software.