Blockchain technology has demonstrated promising practical applications since its inception. From the early days of cryptocurrencies to the current era of smart contracts, blockchain technology has found applications in numerous fields. It effectively addresses trust issues in open networks through decentralized means. The consensus algorithm in blockchain ensures that nodes within a complex network environment can reach an agreement, thereby maintaining the immutability of the node state. This particular algorithm is a cornerstone technology in the realm of blockchain and plays a crucial role in continuous research within this domain. Within this investigation, we aim to clarify the fundamental principles underlying the consensus procedure while classifying diverse consensus algorithms. We delve into the research advancements made in the field of consensus algorithms, and ultimately, we evaluate their performance, discussing the challenges they face and outlining future research directions through a comparative analysis of existing protocols.