Don’t confuse grilling with barbecuing. Grilling simply means to cook over the heat source open to the air. Covering the grill will roast or bake the food but doesn’t help it grill. The heat source can be a bed of charcoal or a row of gas jets or an indoor grill pan. The best grills allow you to adjust the distance of the grill rack from the fire. Thin foods, such as steaks or fish fillets, require intense heat to form a crust before the heat has a chance to penetrate and overcook the interior. The grill rack itself is ideally a heavy metal grid that is flat, not round like wire, which ensures attractive grill markets on steaks and chops. Gas grills have the advantage of requiring no fire building—a fire made with ordinary charcoal briquettes delivers no more flavor than a gas grill—and will still impart a grilled flavor.