From The Bitcoin Reference, the plain-language encyclopedia of Bitcoin vocabulary
The Bitcoin Reference
Welcome to The Bitcoin Reference, a calm and carefully worded encyclopedia of Bitcoin’s vocabulary. Every term here is defined in plain language and in a neutral voice, the way a good teacher would set it out: what the word means, what it does not mean, and which other words it depends on.
Bitcoin is a system for keeping a shared record of ownership without a central record keeper. It has its own words for almost everything it does, and many of them sound alike or borrow ordinary meanings. A block is not a building block, a wallet does not hold coins, and mining digs up nothing. This reference exists to take those words one at a time.
It contains 60 glossary entries across 6 topics, a seven-step reading path for newcomers, and a twelve-question quiz that marks itself and explains every answer. Nothing here predicts, recommends or sells; the aim is understanding, and the content sticks to long-established facts of how the system is designed.
Today’s term
Term of the day
Chosen from the date on your device
Block
A block is a bundle of transactions that miners add to the chain as a single group, together with a header that links it to the block before it.
The term changes once a day. It is picked by a fixed rule from the date on your device, so it is the same all day, and the same term is shown on every visit that day. Nothing is looked up online.
Three ways in
Look something up
The Glossary lists every term from A to Z. Search as you type, filter by letter or topic, and follow the “see also” links from one idea to the next. Each entry has its own address, so you can link a student straight to it.
Learn it in order
The reading path has seven short steps, from the problem Bitcoin addresses to keeping keys safe. Each step names the glossary entries it uses and ends with a question to think over. Your place is remembered on this device only.
Check what stuck
The quiz asks twelve questions, marks each as you go, explains why the right answer is right, and finishes with a review of anything you missed. It is a way to practise, not a test with consequences.
How blocks link together
Most of Bitcoin’s vocabulary hangs from one picture: a Blockchain is a sequence of blocks, and each block carries a fingerprint of the one before it. Figure 1 shows the idea in simplified form. The fields shown are the real contents of a Block header.
An earlier block
- Version
- rules signalled
- Previous block hash
- points further back
- Merkle root
- summary of its transactions
- Time
- when it was found
- Bits
- the target to beat
- Nonce
- the number miners vary
Transactions: a coinbase transaction, then others
The next block
- Version
- rules signalled
- Previous block hash
- fingerprint of the block before it
- Merkle root
- summary of its transactions
- Time
- when it was found
- Bits
- the target to beat
- Nonce
- the number miners vary
Transactions: a coinbase transaction, then others
The block after that
- Version
- rules signalled
- Previous block hash
- fingerprint of the block before it
- Merkle root
- summary of its transactions
- Time
- when it was found
- Bits
- the target to beat
- Nonce
- the number miners vary
Transactions: a coinbase transaction, then others
Taken together, the figure explains several entries at once. The fingerprint is a hash. The summary of transactions is a Merkle tree. The number miners change is the Nonce, and the effort of finding a good one is Proof of work. The first block of all is the Genesis block.
Browse by topic
Every entry belongs to one of 6 topics. Choose any name to open its entry in the glossary.
Foundations 6
Transactions 15
Keys and wallets 11
Blocks and the chain 10
Mining 8
Network and upgrades 10
How this reference is written
Plain first. Each entry opens with a sentence that can stand on its own. Longer explanations follow, and technical detail is added only when it helps the reader.
Neutral and certain. The reference states only long-established facts about how the system is designed, such as the 21 million supply cap, the roughly ten-minute target between blocks, the 210,000-block halving cycle and the use of SHA-256 in proof of work. It does not quote prices, market figures or forecasts, and it does not tell anyone what to buy, hold or avoid.[1]
Corrections welcome. If an entry is unclear or you believe it is wrong, the corrections form on the About page prepares an email to btcsite@appl.dev. The site itself collects nothing.
Notes
- Where reasonable people hold different views, for example on the choice between holding your own keys and using a service, the entry describes the options and the trade-offs, and takes no side. ↑ back to text