Bitcoin and the chain
In 2008 and 2009, Satoshi Nakamoto published a paper for sending value online without a bank clearing the payment. Satoshi Nakamoto is the name on that paper.
A shared ledger
A blockchain is a shared ledger. Transactions are grouped into blocks. Each block is linked to the one before it by a hash, a short fingerprint of the earlier block. If someone changes an old block, the fingerprints no longer match, and the rest of the network can see the break.
No single company keeps the only copy. Many computers hold the ledger, and the network agrees on which chain of blocks is the record.
Buys and sells are UTXO transfers
On Bitcoin, a coin you can spend is an unspent transaction output, called a UTXO. A payment points at outputs you already received and creates new outputs for the next owners. The transfer is broadcast to the network. Miners can put it in a block. It is settled as more blocks are built on top of that one. More confirmations mean more work would have to be redone to change that payment.
Read the source
Bitcoin: A Peer-to-Peer Electronic Cash System (PDF) is the white paper. Bitcoin.org is the project site. Running the software yourself is covered in Running your own node.
Not financial advice. This page is education, as of September 2026. It is not a recommendation to buy, sell, bridge, stake, or sign a transaction, and it is not a promise about price or yield.