Node operators essentially run the chain’s software, certifying transactions as they are entered into the chain by validating new blocks and broadcasting them to the network. Node operators gain rewards for validating new blocks written to the chain. On Polymesh, only a set number of node operators are allowed to validate transactions, determined by how much POLYX is staked to them. Those who do not make it into the winning group miss out on rewards until the next election window (the next day). The idea is that node operators who contribute most and prove most reliable will ultimately win more often, providing incentive for good behaviour while decreasing chances of an adversarial attack.