bitcoin, end-to-end.
a six-stage tour of how value moves through the bitcoin network. scroll to walk through it. takes about four minutes.
the signature
a transaction starts with unforgeable math.
alice wants to send bitcoin to bob. she signs a message — “i’m sending X to bob” — with her private key. that key is a secret only she has.
the signature is math. anyone can verify it belongs to alice without ever seeing her key. and nobody can forge it. she broadcasts the signed message to the network.
the mempool
a waiting room, sorted by fee.
every bitcoin node keeps a pool of unconfirmed transactions, called the mempool. alice’s txlands here alongside everyone else’s.
each tx carries a fee its sender chose. miners pick the highest-fee transactions first, because those earn them the most. if you want into the next block, you pay up.
the puzzle
brute force in an astronomical space.
to add a new block, a miner bundles some mempool transactions and tries to find a number (the “nonce”) such that the block’s fingerprint — its hash — falls below a moving target.
there’s no shortcut. miners just try nonces, one after another, hashing each time. globally, bitcoin miners try hundreds of quintillion hashes every second. on average, one wins every ten minutes.
the reward
new coins, plus fees, on a halving schedule.
the winning miner writes themselves the first transaction in the block — called the coinbase: new bitcoin, plus every fee from every tx they included. today that’s 3.125 BTC, plus fees.
every four years the subsidy halves. it stair-steps down toward zero around 2140. total supply will never exceed 21 millioncoins. monetary policy without a central bank, because it’s carved into the code.
the verdict
thousands of independent validators, no vote.
the winner broadcasts the block. it reaches one node, then another, rippling out across the network in seconds.
every full node independently checks every rule: signatures, scripts, supply math, every tx. if anything fails, the block is silently rejected. consensusisn’t a vote. it’s the absence of disagreement across people who never had to trust each other.
the chain
tampering cascades. the longest valid chain wins.
each new block commits to the previous one by including its hash. change one old block and every block after it becomes invalid — a visible cascade of breakage.
to rewrite history, an attacker would have to redo the proof-of-work for every block since, while the rest of the network keeps extending the honest chain. after six confirmations of depth, a transaction is effectively irreversible. the chain just keeps going.
bitcoin isn’t a pipeline — it’s a loop. the atlas view shows all eight pieces at once, with transactions and rewards flowing between them. click any node to dive in.