To precook is to cook food fully or partially in advance, so that it needs only reheating or minimal finishing before serving. The practice underpins modern food service and manufacturing: par-cooked chips finished to order, sous-vide proteins pasteurised then seared, ready meals cooked then chilled or frozen, and bakery products part-baked for finishing in store. Done well, precooking improves consistency, speed of service, and food safety through controlled time-temperature profiles. Done badly, double cooking degrades texture and nutrition, and the cooling and reheating steps introduce food safety hazards that demand strict controls: rapid chilling through the danger zone, cold storage below 5 °C, and reheating to 75 °C throughout. Cook-chill and cook-freeze systems are the industrial expression of precook logic, feeding hospitals, schools, and airlines safely at scale.