Need of the concept of process: Processes are inert. We know that process is fundamentally the active state of a program which is the set of instruction intended to execute some specific job. Preceding to execution, the instructions should be converted to binary code form inorder to be understood by loader OS. This is stored in the Portable Executable (PE) Format on Secondary Memory such as hard disk in windows this is usually the file with .exe extension
A process consists of a kernel object which keeps statistical information about the process and an address space containing all the executable or DLL module's code, data and dynamic memory allocations such as thread stacks and heap allocations.
The code contained in the process's address space is run by a thread of the process.
One process may contain n number of threads, and all of them execute the code simultaneously in the address space of th process. Each and every thread has its own set of stack and CPU registers.
If no threads were executing the code in the process's address space the system would automatically destroy the process and its address space.