A program on disk is only an idle file. When you run it, the operating system creates a live instance of it, gives it memory and registers it in the list of tasks. That live instance is a "process".
Program or process?#
A recipe for a dish is a program; a cook who is cooking that dish right now is a process. If you open a browser twice, you have one program but two independent processes.
Characteristics of a process#
- A unique numeric ID (PID).
- Separate memory that other processes cannot access.
- A state: running, waiting or stopped.
- It may have several "threads" that work in parallel inside it.
Where do you see it?#
In Windows Task Manager or Linux command-line tools, the list of processes is shown with processor and memory use. If the computer has become slow, often one process is to blame, using a lot of resources.
Notes#
- Closing an unknown process without checking may make the system unstable.
- Malware also runs as processes and sometimes hides under names resembling system processes.
- A process that has hung can be "killed", meaning forcibly closed.