Data & cryptography
Fingerprints, keys and signatures: the maths that lets strangers check each other.
7 cards
Reference cards · one concept each · about three minutes
Blockchain terms explained, one card at a time
What is a hash? What does a node actually do? Why does a network charge something called gas? Each card answers one question: a one-line definition, how it works, a worked example and the mistake people usually make.
Browse the concepts Open the glossary
Educational content only. We do not sell crypto-assets, recommend any, or give financial advice.
- 30 concept cards
- 5 collections
- 89 glossary terms
- 0 prices or charts
Jump to a concept
All cards, A to Z. Pick the word that brought you here.
Five collections
Cards are grouped by the part of the system they describe. Read a whole collection, or just the one card you need.
Blocks & network
Nodes, transactions and blocks: how information moves and gets recorded.
7 cards
Agreement (consensus)
Nonces, proof of work, proof of stake, finality and forks: how strangers agree on one history.
6 cards
Contracts & tokens
Gas, smart contracts, tokens, stablecoins and layer 2: what runs on top of a chain.
5 cards
Safety & rules
Recovery phrases, phishing, 51% attacks, MiCA and the travel rule.
5 cards
Start with these six
The words people search for most often when they first meet the topic. Each one leads naturally to the others.
Data & cryptography
What is a hash function?
A hash function is a calculation that turns data of any size into a short string of fixed length — a digital fingerprint that changes completely if even one bit of the input changes.
Agreement (consensus)
What is a nonce?
A nonce is a "number used once": in proof-of-work mining it is the header field that miners change again and again to get a new block hash, and on Ethereum it is also the counter that numbers each account's transactions.
Blocks & network
What is a node?
A node is any computer that runs a blockchain's software, keeps a copy of its data and exchanges new transactions and blocks with other nodes.
Contracts & tokens
What is gas?
Gas is the unit Ethereum uses to measure how much computational work a transaction needs; the fee a sender pays is the gas used multiplied by a fee per unit of gas.
Blocks & network
What is a block?
A block is a batch of transactions bundled together with a header and added to a blockchain as one unit, once the network accepts it as valid.
Data & cryptography
What is a private key?
A private key is a secret number that lets its holder create digital signatures — and on a blockchain, whoever can sign for an address controls whatever is recorded to it.
How a card works
- 1
One sentence first
Every card opens with a definition short enough to repeat to a friend.
- 2
Then the mechanism
Plain words on how it works, with a small diagram where a picture helps.
- 3
Example and misconception
A concrete case, followed by the misunderstanding people most often bring with them.
- 4
Primary sources
Links to the standards, papers and official texts the card is based on.
Often confused
Some terms travel in pairs and get swapped. Three of the eight pairs we untangle:
Hash vs encryption
Hashing proves sameness; encryption protects secrecy. Bitcoin and Ethereum rely heavily on hashing and signatures, and the public chain itself is not encrypted.
Coin vs token
A coin belongs to the chain itself; a token lives inside a program on the chain. In everyday speech the two words are often used loosely.
Wallet vs address
The wallet is the tool that holds keys; the address is a label others use. Value is recorded on the blockchain, not inside the wallet.
Questions about this site
Is anything on Learning Point Hub financial advice?
No. The cards explain how blockchain technology works. We never suggest acquiring, selling or holding any crypto-asset. For decisions about your money, talk to a licensed adviser where you live.
Why are the cards so short?
Most people arrive with one question, such as "what is a nonce?". A card answers that question in about three minutes and links to the related cards, so you can go deeper only where you want to.
Do you recommend coins, exchanges or wallet apps?
No. We do not review, rank or link to exchanges, wallet products or tokens, and we have no affiliate relationships with crypto companies. Where a real network is named, it is only to illustrate a mechanism.
Who writes the cards?
The Learning Point Hub editorial team. Each card is checked against primary sources such as NIST standards, the Bitcoin whitepaper, Ethereum documentation and EU legal texts, which are listed at the end of the card.
How is the site paid for?
The publisher covers writing and hosting and may advertise the site online. No crypto company pays us, and nobody can pay to be mentioned on a card.
A concept is missing or a card looks wrong. What should I do?
E-mail info@learningpointhub.com with the card address and what you noticed. We read every message and update cards when a correction is needed.
Spotted a gap or a mistake?
Write to info@learningpointhub.com. If a concept is missing, or a card is unclear or wrong, tell us — corrections are handled as described in our editorial policy.