Creating task groups
You can combine two or more tasks into a task group. When you create a group, you define the whether the group task are executed sequentially or in parallel.
Tasks can run in a parallel or sequential pattern. When you create the task, you decide the execution pattern. Tasks without dependencies can execute in any order or simultaneously which is parallel execution. Tasks that must execute in specific order are sequential execution. Tasks are done in list-order starting with the first or top-most task.
You can embed groups within other groups. A sequential-pattern group can be embedded within a parallel-pattern group, and vice versa; however, you cannot embed a sequential-pattern group within another sequential group, or a parallel-pattern group within another parallel group.