Direct vs. Indirect Grilling
There are two methods of using heat to grill:  directly or indirectly. These two methods are very different and  understanding when to use each method is important in making sure that  your dish turns out just right. Direct heat is when you put your dish  directly over the fire and indirect is when your dish is offset from the  source of the heat. The indirect method cooks your meat through  residual heat that is trapped inside the grill. As a basic rule,  grilling any small cut of meat should be done using the direct grilling  method and any large cut of meat should be done indirectly.
Direct Grilling
Cooking  with the direct method is the most common way to grill and is a more  traditional method. Items that are less than 2 inches thick  like steaks,  burgers, hot dogs, shrimp, fish fillets, and chicken  breasts should be  cooked with the direct method and can be positioned directly under the flame of your grill. 
Indirect Grilling
Cooking  with the indirect method is less common and should be used only  for  large cuts of meat like beef brisket, hams, roast, whole chicken  or  whole turkey. Indirect grilling always requires the lid to be closed  in  order to capture the heat inside the grill and cook the meat that  isn't  directly over the flame. Positioning the meat offset from  directly under  the flame allows the meat to cook all the way throughout  the full cut.  If you put a large cut directly over the heat like the  direct method, it  would just burn the bottom side of the meat and the  inside would still  be raw. Cooking indirectly requires a longer period  of cooking time due  to the large portion of meat and the residual heat.