Grilling is a form of cooking that involves dry heat applied to the surface of food, commonly from above or below (as in North America).Grilling usually involves a significant amount of direct, radiant heat, and tends to be used for cooking meat quickly. Food to be grilled is cooked on a grill (an open wire grid such as a gridiron with a heat source above or below), a grill pan (similar to a frying pan, but with raised ridges to mimic the wires of an open grill), or griddle (a flat plate heated from below). Heat transfer to the food when using a grill is primarily via thermal radiation. Heat transfer when using a grill pan or griddle is by direct conduction. In the United States, when the heat source for grilling comes from above, grilling is termed broiling. In this case, the pan that holds the food is called a broiler pan, and heat transfer is by thermal radiation.Direct heat grilling can expose food to temperatures often in excess of 260 °C (500 °F). Grilled meat acquires a distinctive roast aroma and flavor from a chemical process called the Maillard reaction. The Maillard reaction only occurs when foods reach temperatures in excess of 155 °C (310 °F).Studies have shown that cooking beef, pork, poultry, and fish at high temperatures can lead to the formation of heterocyclic amines, benzopyrenes, and polycyclic aromatic hydrocarbons, which are carcinogens. Marination may reduce the formation of these compounds. Grilling is often presented as a healthy alternative to cooking with oil, although the fat and juices lost by grilling can contribute to drier food.