A leave-in thermometer is a kitchen tool designed to monitor the temperature of food while it cooks. It typically consists of a metal probe that is inserted into the food, with a display unit that shows the current temperature. This allows cooks to check the doneness of meats and other dishes without opening the oven or grill, which can cause heat loss. These thermometers are especially useful for slow-cooking methods, such as roasting or smoking, where maintaining a consistent temperature is crucial. Many leave-in thermometers come with alarms or alerts to notify the user when the desired temperature is reached, ensuring perfectly cooked meals.