12.1 Android Applications and Resource Management
Each running Android application is viewed by the operating system as a separate process. If the system identifies that resources on the device are reaching capacity it will take steps to terminate processes to free up memory.
When making a determination as to which process to terminate in order to free up memory, the system takes into consideration both the priority and state of all currently running processes, combining these factors to create what is referred to by Google as an importance hierarchy. Processes are then terminated starting with the lowest priority and working up the hierarchy until sufficient resources have been liberated for the system to function.
