A consensus system aims to ensure that a single value or series of values are accepted and kept consistent across multiple nodes, with the primary guarantee being that once a value is acknowledged as accepted, all other values must be rejected. The goal is to achieve durability at scale without giving absolute guarantees, as no system can provide 100% failure tolerance. A single leader consensus system is used, where the leader accepts requests and makes them durable, and a new leader can be elected to resume requests without divergence or loss of data. The rules governing such systems include accepting a series of requests in strict order, limiting complexity by using a single leader design, and ensuring that at most one leader prevails during concurrent attempts to elect a leader. These rules are intentionally generic to allow for creativity and flexibility in achieving the goals of durability and safety without requiring specific parameters like majority quorums or proposal numbers.