Digital currency systems are a useful case study for this course because almost every component of a cryptocurrency is, underneath the marketing language, a familiar data structure doing a specific job. A wallet is essentially a key-value store mapping keys and addresses to spendable funds. Pending transactions sit in a mempool, a priority-ordered holding area that nodes draw from. Confirmed transactions are summarized by a Merkle tree so that membership can be verified with a short proof instead of a full scan, and blocks are chained together much like a linked list in which each node stores a hash pointer to its predecessor.
Two accounting models dominate. In the UTXO (unspent transaction output) model used by Bitcoin, a wallet balance is not a stored number at all but the sum of a set of discrete unspent outputs, each of which must be consumed whole and replaced by new outputs. In the account model used by Ethereum, balances are stored directly in a mutable key-value map. The choice between these shapes everything downstream: storage size, lookup cost, parallelism, privacy, and how easily the system scales.
As you watch the videos below, keep translating the vocabulary back into course terms. When you hear "UTXO set," ask what structure holds it and what the cost of a lookup or update is. When you hear "hash," ask what properties make it suitable for linking blocks and for building Merkle trees. When you hear about fees and consolidation, ask what trade-off is being made between storage footprint, computation, and user privacy — that habit of naming the trade-off is exactly what the module assessments will ask for.
A short, comparative explainer contrasting the two dominant bookkeeping models in blockchains: UTXO-based systems such as Bitcoin and account-based systems such as Ethereum. Based on its title and description, it should walk through how each model represents a balance, how a transaction changes state under each, and where the practical differences show up.
It directly supports the Transaction Data and the UTXO Model subtopic and gives you the side-by-side framing you need to discuss storage and lookup trade-offs rather than treating UTXO as the only option.
A longer, practice-oriented walkthrough of Bitcoin UTXOs from a hardware wallet maker, focused on what a UTXO actually is and how the set of UTXOs a wallet controls affects transaction fees and privacy. The description points toward UTXO consolidation — combining many small outputs into fewer larger ones — as a concrete management technique.
Coming from Trezor, a wallet producer, it grounds the abstract UTXO model in real wallet behavior and makes the data-structure trade-off tangible: more entries in the set means larger transactions, higher fees, and different privacy properties.
An episode from a short serialized explainer series that steps aside from the ongoing payment story to look at the hashing algorithm itself. Expect coverage of what a cryptographic hash function does to an input and why its output behaves the way it does in a Bitcoin context.
Hashing is the primitive that makes hash pointers, block chaining, and Merkle trees work, so this brief piece fills in the foundation that the Merkle tree and linked-list-of-blocks subtopics build on.
Together these videos feed primarily into MO1 and MO4. The hashing episode supplies the cryptographic primitive that underlies hash-linked blocks and Merkle proofs, which is the foundation MO1 asks you to explain. The two UTXO videos give you both the conceptual model and its real-world consequences, so that when MO4 asks you to evaluate the structural design decisions of a digital currency platform you can name the actual structures in play — key-value stores for wallets and account balances, a UTXO set, a mempool — and articulate concrete trade-offs in storage, fees, and privacy. They also build the comparative vocabulary you will reuse in MO5 when justifying your own multi-structure design against stated requirements.
These videos were chosen from YouTube on October 2, 2026. Each has captions; the player turns them on. Videos on YouTube can be changed or removed — if one no longer plays, tell your instructor. If a player does not appear, use its Watch on YouTube link.