The whole point of IPC – or Inter Process Communication – is to provide efficient and flexible message passing communication mechanisms between processes.
These are the five primary IPC mechanisms available:
Processes can connect using TCP/IP or UDP sockets and exchange data over the sockets.
A pipe is used for one way communication of a stream of bytes.
When a single block of memory in the address space is shared by two or more processes then that is considered to be shared memory. If one process changes this shared memory then that change is visible to all of the other processes with access to the shared memory.
With message queues, one or more processes can write messages, which can in turn be read by one or more reading processes.
Signals are one of the oldest interprocess communication methods, and are used by Unix systems. They are used to signal asynchronous events to one or more processes.