Glossary
Practical Byzantine Fault Tolerance (PBFT)
The foundational 1999 BFT consensus algorithm by Castro and Liskov — three-phase voting protocol tolerating up to one-third Byzantine nodes with deterministic finality.
PBFT, introduced by Miguel Castro and Barbara Liskov in 1999, was the first practical Byzantine-fault-tolerant consensus algorithm — tolerating up to one-third malicious nodes in a permissioned validator set with deterministic finality. The algorithm runs in three phases per round (pre-prepare, prepare, commit) with all-to-all messaging.
The all-to-all communication makes vanilla PBFT O(n²) in message complexity, which is why most production systems use modifications (HotStuff, Tendermint, CometBFT, Tower BFT) that reduce the overhead. PBFT remains the foundational reference design for BFT-style consensus.