Consensus Mechanism

A consensus mechanism is the set of rules and procedures that all the computers in a blockchain network follow in order to agree on which transactions are valid and what the correct history of the ledger looks like. Because blockchain networks have no central authority, all the participating computers must somehow arrive at the same truth on their own. The consensus mechanism is the engine that makes this possible.

Different blockchains use different types of consensus mechanisms. Bitcoin uses Proof of Work, where computers compete to solve difficult mathematical puzzles. Ethereum switched to Proof of Stake in 2022, where validators lock up their own cryptocurrency as collateral to prove their commitment to honesty. Other systems use variations like Delegated Proof of Stake or Proof of Authority. All of them are trying to solve the same underlying question: who gets to write the next page of the shared history, and how can everyone be confident it has not been manipulated?

Example: Imagine a group of accountants who all keep identical copies of a shared ledger. Before anyone writes a new entry, they all need to agree it is legitimate. The rules they use to reach that agreement are the consensus mechanism. Blockchain networks do the same thing, just across thousands of computers around the world.