Byzantine Fault Tolerance (BFT) is the ability to tolerate failures in distributed computing systems. The term originated from the hypothetical phenomenon known as the Byzantine Generals Problem. It describes a situation where, in order to prevent the failure of a distributed system, the system’s actors must agree on the same strategy.
The objective of the BFT mechanism is to defend a network from a system failure. In the case of a peer-to-peer (P2P) network, such as a blockchain, transactions are deemed valid only if a group of nodes agrees it is. To achieve that consensus, each blockchain network implements its own consensus mechanism that determines the rules.
For example, Bitcoin uses the consensus algorithm known as Proof of Work (PoW), where miners compete amongst each other to solve mathematical puzzles. The first miner to solve the equation earns the right to add a block of transactions to the blockchain and gets rewarded in newly minted BTC, the native asset. It is through the use of this consensus mechanism that a network becomes Byzantine Fault Tolerant.
The BFT system states that, as long as two-thirds of the nodes within a network are functioning as they should, the network will continue to operate. As a result, the BFT system greatly reduces the risks of node failures and malicious attacks.
