What is a process? What are attributes of a process?

A process is one or more threads of execution that exist in a single virtual memory space. A process has it's own set of file descriptors, virtual memory space, timekeeping data, etc.

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1. a program in execution
2.an instance of running program
3. an owner of the resource allocated to program execution
4. a task or a job
5. en-compass one or more threads 

Attribute of a process:

• Address Space
• Open files - (could be argued are part of  resources)
• Process ID
• Process Group
• Parent Process
• signals etc.

Attributes of  threads:

• Scheduling Parameters
• Registers
• Program Counter
• Program Status Word
• Stack Pointer
• Thread state

If the OS does not support multi-threaded applications, then thread attributes become process attributes.