multitasking is supported through seven background APIs:

Background audio – application continues to run in the background as long as it is playing audio or video content

Voice over IP – application is suspended when a phone call is not in progress

Background location – application is notified of location changes

Push notifications

Local notifications – application schedules local notifications to be delivered at a predetermined time

Task completion – application asks the system for extra time to complete a given task

Fast app switching – application does not execute any code and may be removed from memory at any time