The validator set is the current group of validators participating in consensus. The maximum number of validators in a set is 19, and a new validator set is chosen for each staking epoch. Members are selected based on the total amount of stake in their pool relative to the total deposited stake (stake ratio), along with a random number that adds variation to the process. A higher stake ratio results in a higher likelihood of selection, but it does not guarantee selection, as every active candidate has a chance to be selected to the next set.