A process represents an execution process of a program. It is a running instance of an application program and a dynamic process. Or it can be more simply described as: a process is a program currently running by the operating system. When a process starts to run, it starts. The process consists of two parts: dynamically executed programs and data. Modern operating systems support multi-process processing. These processes can accept the scheduling of the operating system, so each process is an independent unit of the operating system for resource scheduling and allocation.
All processes may have three states: running state, ready state and blocking state.
The running state indicates that the program currently actually occupies CPU and other resources;
Ready state means that all running resources of the program except CPU are ready, waiting for the operating system to allocate CPU resources, so long as CPU resources are allocated, the program can run immediately.
Blocking state refers to the process in which the program cannot continue to execute due to the need to request external resources (such as I/O resources, printers and other low-speed or exclusive resources at the same time), thus actively abandoning the current CPU resources and waiting for the requested resources.