There are a few different methods of grilling with your gas grill, your charcoal grill, or your bbq smoker.
There is direct grilling, indirect grilling, and smoking.
Let us start with direct grilling.
Direct grilling involves cooking your food inches over the flames. This would be done with thin cuts of meat, fish, shellfish & fruit or vegetables. These foods tend to cook quickly and can benefit from the searing heat of the flames.
With this method of cooking you generally do not need the lid of your cooker, and should stand close watch over the food to make sure it does not burn. You should never leave your grill unattended anyway, but direct grilling takes a much closer watch. You also want to make sure that you have separate heat zones. A heat zone is a way to control temperature. This is so you have an area to direct grill or even sear your food, an area to cook the food, and so you have an area to put food that is already done or almost finished. More or less, your safety zone.
If you are cooking for a larger crowd, you will want three cooking zones. One for searing, one for cooking, and