Recently, blockchain is the most familiar trusted transaction service used to achieve better cooperation in a decentralized application environment. Most of the financial, internet of things, and non-financial applications depend on blockchain technology to accomplish a secured decentralized distributed database. The blockchain architecture comprises two main blocks that are block and digital signature. The block comprises numerous subfields like block version, Merkle tree root hash, timestamp, nBits, nonce, and parent block hash. The digital signature comprises a pair of public and private keys. Blockchain protocols can control the activity of the corresponding blockchain network. The blockchain comprises various types of consensus algorithms that are mainly categorized into permissionless consensus and permissioned consensus. The consensus protocols of blockchain are listed below.