Core Concepts Flashcards
7 cards from real Blockchain Technology practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Core Concepts flashcards as text
What is the significance of the 'longest chain rule' (Nakamoto Consensus) in Bitcoin?
Answer: Nodes always follow the chain with the most cumulative proof-of-work as the valid chain
Nodes adopt the chain representing the greatest cumulative computational work, making it economically infeasible for attackers to rewrite history.
How does sharding improve blockchain scalability?
Answer: By splitting the network into smaller partitions that process transactions in parallel
Sharding divides the blockchain state and transaction load across multiple shards that process transactions simultaneously, increasing overall throughput.
What is the difference between on-chain and off-chain transactions?
Answer: On-chain transactions are recorded directly on the blockchain; off-chain occur outside the blockchain and may settle later
On-chain transactions are broadcast and recorded on the main blockchain, while off-chain transactions (e.g., Lightning Network) happen externally and only settlement may be recorded on-chain.
What does 'deterministic wallet' (HD wallet) mean in blockchain?
Answer: A wallet that generates all key pairs from a single master seed phrase in a predictable tree structure
HD (Hierarchical Deterministic) wallets derive an unlimited number of key pairs from one seed phrase, making backup and recovery simpler.
What problem does a blockchain oracle solve?
Answer: It provides smart contracts with real-world external data that the blockchain cannot access natively
Oracles bridge the gap between blockchains and the external world, feeding smart contracts data like prices, weather, or sports results.
What is the 'block reward halving' event in Bitcoin, and what is its economic purpose?
Answer: A periodic reduction of the Bitcoin mining reward by 50%, controlling the issuance rate toward a fixed supply cap
Every ~210,000 blocks (~4 years), Bitcoin's block reward halves, slowing new coin issuance and enforcing the 21 million BTC supply cap.
In blockchain networks, what is the purpose of a mempool (memory pool)?
Answer: A temporary holding area where unconfirmed transactions wait to be selected by miners into a block
The mempool is each node's local queue of broadcast but unconfirmed transactions awaiting inclusion in the next block.