In a traditional gas grill, flames heat the grates directly; however, with infrared grills, there is an infrared element between the grates and flame. The gas heats this infrared element, which then radiates intense heat to the food.
Infrared burners get extremely hot, extremely fast. In under 10-minutes, they can reach temperatures upwards of 700°F, allowing you to get a deep sear on meats and vegetables. An additional benefit is that food retains more of their natural juices and there’s less of a chance of flare ups.
These types of burners are usually found on the back or side of a gas grill as an extra cooking surface. The Napoleon Prestige Series has models of grills that include an infrared sizzle zone which makes grilling a variety of foods easy and impressive.