Delivery Methods are a way to distinguish between various types of events and whether or not to charge for certain things (such as staff/attendants or distance charges). The 3 most common are "Fully Staffed", "Drop off", and "Customer Pickup." However, there are many smaller settings in delivery methods which may make it useful to add in more Delivery Methods.
You can set up certain restrictions for different Delivery Methods. For example, you can set default start and end time and decide whether or not the customer can change these. If you have multiple quote forms, you can exclude Delivery Methods from certain forms so that the customer cannot choose this Delivery Method. You can also list specific items that you do not allow for a Delivery Method.