|Code| Processes communicate by IPC methods

Threads can shares the same resources such as address space, file descriptors, stack and other process related attributes in the same process.
BUT Processes can not share resources directly.

Processes will communicate to each other by IPC method.
There are two ways:
 1. Shared Memory
 2. Message passing: Socket, FIFO, POSIX message, dbus

The following methods, which we often see, belong to message passing.
Remote Procedural calls (RPCs)

Originally, I though it is a basic interview question and everyone has at least a common answer .
Until I found someone did not know , I know I was wrong.