Fourth, the programs can run concurrently, allowing a report to be run while the address book finds and displays addresses. Finally, data is not the only shared element. Now imagine putting the address book on one machine, the report writer on another, and the database server on a third, and having them all work as if they resided in the same machine. Such a network-intrinsic application changes the face of computing. IPC An understanding of the tools of interprocess communication is essential.
Shared memory is a portion of memory that multiple processes can access.
Process A puts data into the shared memory space. Then Process B gets it out. Flags are signals that processes give to each other. One process issues a flag and the others look out for that flag. When it is received, a particular action is taken.