Minimizing is probably one of the most common transitions that an app undergoes. It's the transition from a full screen state to a thumbnail state.
These are the navigator events sent when an application is minimized:
The following diagram shows the events that are received when the app is
minimized: 
Your code needs to handle the reception of each of the above events and properly respond to each of them. For more information regarding each of these events, see Various States and BPS Navigator Events sections.