Practical Byzantine Fault Tolerance

Practical Byzantine fault tolerance, or pBFT, is a consensus algorithm that lets a known set of nodes agree on an ordering of transactions through several rounds of voting, tolerating faulty or malicious members as long as fewer than one third of them misbehave. Nodes exchange pre-prepare, prepare and commit messages, and once enough matching votes are collected the result is final immediately rather than settling probabilistically over time. That instant finality suits permissioned and consortium chains, and pBFT-derived designs appear inside several proof-of-stake networks. The limitation is communication cost: message volume grows sharply with validator count, so pBFT-style protocols usually operate with modest, known validator sets.