ABSTRACT
Blockchain technology enables users to access a shared ledger whose status is preserved intact in a decentralized manner by the network. To ensure a common, clear ordering of data transaction, blockchain uses a consensus mechanism. Consensus protocol ensures blockchain’s reliability and integrity across the network. Bitcoin, which first popularized the concept of blockchain, also uses a consensus mechanism called “proof of work” (PoW), which is applied to thousands of nodes within the network. PoW is a tough cryptographic puzzle to be solved by a miner to add a block to the blockchain. Consensus protocol is solely responsible for maintaining a clean data in blockchain. This chapter provides an overview of the consensus models, narrates the transaction process using consensus, and examines the different consensus attacks.
