Byzantine Generals Problem

The Byzantine Generals Problem highlights the challenge of getting independent actors in a distributed system to agree on a single course of action, especially when some participants might be unreliable or malicious. The classic illustration involves generals surrounding a city, who must coordinate an attack. Their dilemma is complicated by the risk that some messages may be intercepted, delayed, or falsified, so there’s no way to guarantee who can be trusted.

In digital networks, such a scenario makes it difficult to reach reliable, trustless consensus. Bitcoin addresses this through Proof-of-Work: each block on the blockchain is only accepted if it includes a valid cryptographic hash, serving as evidence that substantial computational effort was expended. This process helps prevent fraudulent or empty blocks since generating them requires real resources, and honest miners are motivated by rewards and fees to follow the rules. As a result, decentralized nodes can maintain agreement on the state of the blockchain without relying on a central authority.