Defined as any agreement by a given majority, often placed at 51%. If 51% of people, or entities on a network, agree to a certain condition, be that a value transaction or change to the system, the result is known as consensus. An important part of the cryptocurrency space, consensus is required to verify the validity of digital transactions on a blockchain. It is also a way of politically managing decentralized systems, for instance whether or not a hard fork should occur.