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Byzantine Fault Tolerance

The ability of a distributed system to reach agreement even when some participants fail or behave maliciously.

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Definition

The ability of a distributed system to reach agreement even when some participants fail or behave maliciously.

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Why it matters

Consensus concepts explain how independent nodes agree on one shared history without a central coordinator.

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How it works

The system uses multi-round voting mechanisms to reach agreement. Nodes exchange cryptographically signed messages about the validity of data. A block is only added if a predefined supermajority of nodes confirm they have seen and validated the same data, effectively ignoring the dishonest minority.

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Real-world example

The Cosmos SDK and Tendermint Core are prominent modern examples of BFT-based consensus frameworks in production.

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Advantages

  • Resilience against arbitrary node behavior
  • Cryptographic verification of state
  • High level of trustlessness

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Limitations

  • Communication costs scale poorly
  • Network latency sensitivity
  • Risk of stalls in high-churn environments

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Common misconceptions

  • It is a myth that BFT applies only to leader-based protocols. Many people falsely believe that BFT automatically provides censorship resistance.
Canonical knowledge ID: glossary:byzantine-fault-tolerance