Concept collections
The same thirty cards, grouped by the part of the system they describe.
Collection 1 · 7 cards
Data & cryptography
Before blocks or networks, there are a few cryptographic tools. Hash functions turn data into fingerprints, key pairs let people sign without revealing secrets, and addresses are built from both. These seven cards cover the building blocks that every other collection relies on.
Collection 2 · 7 cards
Blocks & network
A blockchain is kept by many computers talking to each other. This collection follows a transaction from the moment it is signed, through the waiting room of the mempool, into a block — and explains how blocks are linked, starting with the very first one.
Collection 3 · 6 cards
Agreement (consensus)
Thousands of independent computers must agree on which block comes next, without a referee. These six cards explain the two main methods for reaching that agreement, the people and machines who take part, and what happens when the network briefly disagrees.
Collection 4 · 5 cards
Contracts & tokens
Some blockchains do more than record transfers: they run programs. This collection explains how those programs are metered, what tokens really are, how stablecoins are designed to hold their value, and how layer-2 systems try to handle more activity.
Collection 5 · 5 cards
Safety & rules
Technology does not exist in a vacuum. These five cards explain the most common way people lose control of their keys, what a majority attack can and cannot do, and the two sets of rules that shape crypto-asset services in Europe and beyond.