Question 1

Why is Bitcoin's block time 10 minutes?

Accepted Answer

Satoshi Nakamoto chose 10 minutes as a balance between confirmation speed and network propagation time. Blocks need time to propagate across the global network — if block time were too short, miners would frequently produce competing blocks (orphans), wasting energy and reducing security. The 10-minute target gives enough time for blocks to reach most nodes before the next block is found.

Question 2

What is block finality?

Accepted Answer

Finality is the point at which a transaction is considered irreversible. In proof-of-work chains, finality is probabilistic — each subsequent block makes reversal exponentially harder. Bitcoin transactions are typically considered final after 6 confirmations (~60 minutes). In proof-of-stake chains like Ethereum, finality is achieved through validator attestations, typically within 2 epochs (~13 minutes).

Question 3

How does block time affect transaction throughput?

Accepted Answer

Transaction throughput equals block size divided by block time. A chain with 1 MB blocks and 10-minute block time processes fewer transactions per second than one with 1 MB blocks and 12-second block time. However, simply reducing block time has trade-offs: it increases bandwidth requirements, can lead to more chain reorganizations, and may centralize mining or validation to better-connected nodes.

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