The concept of blockchain, widely known as virtual currencies, saw a massive surge in popularity in recent times. As far as the security of the blockchain is concerned, consensus algorithms play a vital role in the blockchain. Research has been done separately, or comparisons between a few of them have been presented previously. In this paper, we have discussed widely used consensus algorithms in the blockchain. The consensus protocols covered in this paper include PoW (Proof of Work), PoS (Proof of Stake), DPoS (Delegated Proof of Stake), PoET (Proof of Elapsed Time), PBFT (Practical Byzantine Fault Tolerance), and PoA (Proof of Authority). For each consensus, we have reviewed the properties, applications, and performance in the blockchain.