Blockchain is a decentralized system with no central authority. This makes the system non-corrupt, but creates difficulties with the final decision making and organization of work. These problems could be solved by a consensus mechanism, which is a way to reach agreement in a group of participants. Voting takes in account the majority opinion without interests of the minority, but on the other hand, it guarantees an agreement that benefits the entire network.
You can choose the consensus mechanism during the initial configuration of the network. The description of available mechanisms, as well as their pros and cons, are described in the relevant sections.