When service process, background process & empty process. In

an application component starts and the application does not have any other
components running, both operating systems starts a new process for the
application with a single thread of execution. In both OS By default all
components of the same application run in the same process and thread (called
the “main” thread) in android main thread is called UI thread. Each
process is made up of one or more thread which run dependently or independently
and every thread use the same virtual memory and address space of the process.
In android all components of the same application run in the same process and
most applications should not change this if to control which process a certain
component belongs to, this can be done in manifest file. If a new application need
to start and there is not enough space in the memory then both the OS android
and iOS forcefully shut down the process according to their importance to
create space for new process. There is a hierarchy of processes to determine
which process will be killed first or last while system is low on memory, in
android foreground process, visible process, service process, background
process & empty process. In iOS the hierarchy is same like this foreground
processes, background processes, suspended processes & not running
processes, the list is based on “importance hierarchy”  it mean importance of first process is high
so it will be killed at last while last one killed first. There are different
states of a process, in android states are created, running, Paused, stopped
& killed, in iOS states of process is Not running, active, inactive, background
& suspended. Android provides a proper mechanism for inter process
communication IPC through RPCs Remote procedure calls, in which a method is
called by an activity or other application component, but executed remotely (in
another process), with any result returned back to the caller. In iOS two
techniques are used for IPC which is Grand central dispatch and pasteboard. In
both Operating systems processes can perform I/O operations.