How a blockchain works: key words
Read the word, say the meaning out loud, then open the card.
Hash function
A function that turns data of almost any size into a short code of fixed length, called a digest. Source
SHA-256
A hash function from a US standard, FIPS 180-4. Its digest is 256 bits long. Bitcoin uses it. Source
Block
A batch of transactions plus a header that describes it, including the hash of the block before. Source
Genesis block
The first block in a blockchain. It has no block before it. Source
Node
A computer in a blockchain network that runs the network's software and connects to other nodes. Source
Full node
A node that stores the blockchain and checks that transactions and blocks are valid. Source
Nonce
A number used only once. In proof of work, miners change it to get a new hash. Source
Proof of work
A way to agree on new blocks: the first computer to solve a hard guessing puzzle adds the next block. Source
Proof of stake
A way to agree on new blocks: users lock up coins, and their chance of adding a block depends on their share of the stake. Source
Validator
On Ethereum, a user who has deposited at least 32 ETH and runs software to check and propose blocks. Source
Confirmation
On Bitcoin, a transaction gains one confirmation for each block, starting with the block that includes it. Source
Finality
The point at which a transaction is in a block that can no longer change. Source