In a centralised system where information is stored on a database, any maintenance and updates are carried out by a central authority. This single administrator has the capacity to carry out operations like addition,deletion and updating of data in the database regardless of people who own the data. But there is a way agreement can be achieved in data recording without a single authority in charge and this is known as consensus mechanism.
Consensus mechanism is used in data recording. It used to achieve agreement on data or network on a computer or blockchain systems. Consensus mechanism are usually tolerant to fault. Apart from being used for record keeping, it is used for a variety of other things. On a blockchain, consensus mechanism make sure that all participants do not violate the rules and the transactions are kept secured.
Different types of consensus mechanisms are proof of work(POW), proof of stake(POS), delegated proof of stake(DPOS), proof of capacity(POC) and a lot more.