Mining and Transaction Lifecycle Flashcards

What happens to a Bitcoin transaction before it is included in a block?

Answer: It waits in the mempool

Unconfirmed transactions sit in the mempool (memory pool) until a miner selects and includes them in a block.

Which hashing algorithm does Bitcoin's proof-of-work system use?

Answer: SHA-256

Bitcoin uses SHA-256 (Secure Hash Algorithm 256-bit) for its proof-of-work mining process.

What is a 'stale block' in cryptocurrency mining?

Answer: A valid block that was mined but not accepted because another block was found first

A stale block is a correctly solved block that arrives too late because another miner already found and broadcast a valid block at the same height.

What does 'transaction throughput' measure in a blockchain network?

Answer: The number of transactions processed per second (TPS)

Transaction throughput, measured in TPS (transactions per second), indicates how many transactions a network can process in a given time period.

In Bitcoin mining, what is the purpose of the 'nonce'?

Answer: To vary the block header input so miners can find a valid hash

The nonce is a 32-bit number that miners increment repeatedly to produce a block hash that meets the network's difficulty target.

What is 'selfish mining' in the context of cryptocurrency?

Answer: Withholding discovered blocks to gain a competitive advantage over honest miners

Selfish mining is a strategy where a miner or pool withholds newly found blocks to force honest miners to waste effort on an already-solved block.

Which of the following best describes an 'orphan block'?

Answer: A valid block that is not part of the longest chain

An orphan (or uncle) block is a valid block that was mined but is not included in the main canonical chain because a competing block at the same height was accepted instead.