Blockchain exists because of consensus. It enables mutually untrusted nodes to agree on a shared state without a central authority.
Trust shifts away from people and institutions toward cryptography, protocol rules, and economic incentives where dishonest behavior is costly.
Byzantine Fault Tolerance
Consensus mechanisms are built under Byzantine assumptions, ensuring correctness even when some participants act maliciously.
PoW and PoS
PoW relies on energy costs while PoS relies on staked capital and slashing. Each represents deliberate architectural trade-offs.
