You have seen feedback loops before in their infrastructure form: health checks that trigger service restarts, auto-scaling that adjusts capacity to observed load, circuit breakers that halt requests to failing dependencies. In each case, a measured signal drives a corrective action. This chapter examines the feedback loop at the product layer, where the measured signals are product metrics and the corrective actions are prioritisation decisions. The engineering challenge is identical: choose the right signal. A feedback loop driven by the wrong metric will optimise the wrong thing as reliably as a loop driven by the right metric will optimise the right thing.