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What is Bitcoin?
Bitcoin is the first decentralized peer-to-peer payment network, and bitcoin (lowercase) is the digital money that moves on it. No single person or company owns or runs it, and the protocol limits the total supply to 21 million bitcoin.
What it means for you
A confirmed bitcoin transaction is irreversible; only the recipient can refund it. Bitcoin divides to eight decimal places (one satoshi is 0.00000001 BTC), so you can send or buy a fraction of a coin rather than a whole one.
A common mistake: “Bitcoin is anonymous, so payments can't be traced.”
In fact: Bitcoin's own FAQ says it is not anonymous: every transaction is kept in a public ledger. Once an address is linked to a person, through an exchange record or a shared address, its whole payment history can be followed.
How it works
Miners extend the ledger by hashing a candidate block header over and over until the result falls below a target. Every 2,016 blocks the network recalculates that target from how long those blocks took, keeping the average near 10 minutes per block. The first transaction in each block pays the miner newly created bitcoin plus fees; the new-coin part halves every 210,000 blocks, so issuance stops near 21 million. Nodes follow the valid chain with the most accumulated work, and each balance is a set of unspent transaction outputs locked to keys.
The founding paper
Bitcoin: A Peer-to-Peer Electronic Cash System Whitepaper · 2008 · Satoshi Nakamoto
Sources: bitcoin.org: Frequently Asked Questions, bitcoin.org: Bitcoin: A Peer-to-Peer Electronic Cash System, Bitcoin developer guide: Block chain, BIP 42: A finite monetary supply for Bitcoin, Bitcoin developer guide: Transactions · checked 4 October 2026
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