The first rule blockchain nodes must agree to is how to allow new blocks to be added to the blockchain. Because no node has more authority than any other node, the nodes use consensus to agree to add new blocks. Consensus in this sense simply means that when enough nodes agree to take some action, that the action is approved and agreed upon by all nodes. Most consensus strategies use simple majorities to succeed. So, as long as more than half of nodes agree to take some action, the action is approved
The consensus algorithm is the method of gaining consensus on a change of data over the system or distributed network. Consensus algorithms are heavily used in blockchains as they enable the network of unknown nodes to reach consensus on the data that is being stored or shared through the blockchain.
There are many types of consensus algorithms or techniques available. The most popular consensus algorithm is:
