blockchain information

What is DigiCash (1989)?

David Chaum’s anonymous digital currency

What is e-Gold (1996)?

gold-backed digital currency, gold was held in deposit boxes and digital currency was exchanged with smart contracts

What about Beenz and Floorz (1990s)?

Dotcom era digital currencies

What is public key cryptography (RSA, ECC)?

Asymmetic Encryption! You have a private key that no one knows about but you, and public key attached to you that everyone can know

Cryptographic hashing (SHA-256)

one-way functions that scramble data, hashes scramble data consistently without being reversible. no input shares a hash with any other input

What is a digital signature?

authentication and non-repudiation. you authorize a transaction, and other people can verify it.

What is a merkle tree?

efficient data verification

What was the common problem with early forms of blockchain?

the “double-spending problem”

What type of encryption is public key cryptography?

asymmetric encryption

Who made BitCoin?

Satoshi Nakamoto, but his real identity remains unknown

Is Distributued ledger technology centerally controlled?

DLT or Distributed ledger technology is not centerally controlled

What is the immutable record of transactions, and how is it secured?

The ledger of transactions bitcoin goes through, and it is cryptographically secured

What is the consensus mechanism?

agreement without central authority

what does decentralized architecture help with?

no single point of failure

How does transparency with privacy work?

pseudonymous, but they can be auditable or identified with some detective work

What is a transaction initation?

user creates and signs transaction with private key

what are the steps of adding a block to the chain?

transaction initiation, broadcasting, validation, mempool, mining/consesus, block creation, chain addition and finality

what is broadcasting?

transaction sent to peer-to-peer network of nodes

what is validation?

network nodes verify transaction is legitimate

what is the mempool?

validated transactions wait to be included in next block

what is included in the mining / consensus process?

nodes compete (proof of work) or are selected (proof of stake) to create next block

what is block creation in blockchain?

the transactions bundled with timestamp and cryptographic hash of previous block

how does a chain get added into the blockchain?

new block broadcast and accepted by network

what is the finality step in the process of adding a block to the blockchain?

the very last step! where the transaction becomes part of permanent record

what is the question of the byzantine generals problem?

how do distributed nodes reach agreement when some are faulty/malicious?

what is the byzantine fault?

a node fails in an arbitrary, unpredictable way (not just crashing)

what is the BFT tolerance limit?

systems can tolerate up to 1/3 of nodes being faulty or malicious

what is the practical byzantine fault tolerance (PBFT) algorithm?

foundational consensus approach

what are the quorum requirements?

majority of honest nodes must agree

what is the connection to blockchain and consensus?

consensus mechanisms are solutions to BFT

what is the “proof of work” in the consensus?

solving a difficult computational puzzle to earn rights to create a block

what type of model did bitcoin and etherum originally use?

the proof of work consensus, where you had to solve a difficult puzzle and use large amounts of energy to do so, but were economically incentivized

how much power does bitcoin use alone?

as much power as all of sweden

what is the fixed supply cap of bitcoin?

21 million bitcoins maximum (scarcity by design!)

what does bitcoin do to keep scarcity?

halving events, where mining rewards decrease every four years, and no more bitcoins will be created after 2140

what is the store of value focus for bitcoin?

the “digital gold” narrative is heavily used

how much is annually spend on mining bitcoin (as of 2026?)

$15 billion

who created ethereum?

vitalik buterin in 2015

what is ethereum?

decentralized blockchain with smart contract functionality.

what is a smart contract when talking about ethereum?

self-executing code on blockchain

what is turing-complete in the ethereum context?

can run arbitrary programs

what did ethereum do?

enabled explosion of decentralized applications (dApps)

what is decentralized finance (DeFi)?

financial services without traditional intermediaries, such as banks, brokers and exchanges

what is a lending protocol for DeFi?

collateral provided, interest earned algorithmically

what does decentralized exchanges (DEXs) mean in the DeFi context?

automated market makers enable peer-to-peer trading

what do derivates and options trading do in the DeFi context?

sophisticated financial instruments on blockchain

what is yield farming and liquidity provision?

users earn returns on capital

what are the risks associated with decentralized finance (DeFi)?

smart contract bugs, flash loans, impermanent loss, regulatory uncertainty

What are most NFTs built on?

Ethereum network

What is an NFT, and what does it stand for?

Non-Fungible Token, and it is a unique digital asset with provable ownership

What are some of the use cases of digital ownership?

digital art, collectibles, gaming items, domain names, even things like boredapeyachtclub and cyptopunks

What type of blockchain helped Walmart track down food poisoning cases much more efficiently?

IBM’s Food Trust blockchain