Practical Byzantine Fault Tolerance (PBFT) is a consensus algorithm designed to ensure reliable communication in distributed systems, even when some nodes may fail or act maliciously. It allows a network of computers to agree on a single value or state, ensuring that the system can continue to function correctly despite the presence of faulty nodes. PBFT works by requiring a majority of nodes to agree on the validity of transactions. It operates in a series of rounds, where nodes exchange messages to reach consensus. This method enhances the resilience of systems like blockchain and distributed databases, making them more robust against failures and attacks.