Program

A program is a set of instructions written in a programming language to perform a specific task. It exists as a static entity, typically stored on non-volatile storage like a disk, until loaded into memory for execution by the operating system.

Process

A process is a program under execution (which is currently running). The program counter (PC) shows the address of the next instruction in the executing process. Each process is identified and managed by a Process Control Block (PCB).

Process Scheduling

Process scheduling in operating systems is the task of managing CPU allocation to different processes, determining which process runs next, and when. It's a critical function in multiprogramming systems where multiple processes share the CPU simultaneously.

1. Arrival Time – Time at which the process arrives in the ready queue.
2. Completion Time – Time at which process completes its execution.
3. Burst Time – Time required by a process for CPU execution.
4. Turn Around Time – Time difference between completion time and arrival time.
   • Turn Around Time = Completion Time - Arrival Time
5. Waiting Time (WT) – Time difference between turn around time and burst time.
   • Waiting Time = Turnaround Time - Burst Time