A process is a fundamental concept in operating systems (OS) representing a program in execution. It encompasses the program code, its current activity, and the necessary resources such as memory, files, and I/O devices required for its execution. Processes are dynamic entities that transition through various states, including new, ready, running, waiting, and terminated as they progress through the system’s scheduling and execution phases.

A process is defined as an instance of a program in execution, comprising the executable program code, its associated data, and the execution context required by the operating system to manage its execution. Formally, a process can be represented as a tuple:P=(C,D,S)P = (C, D, S)P=(C,D,S)

where:

• CCC represents the program code segment or instructions.
• DDD denotes the process-specific data segment, including variables and allocated memory.
• SSS is the execution context, which contains the state of the CPU registers, program counter, process state, and other scheduling information.

The operating system maintains control and information about each process through a Process Control Block (PCB). A process undergoes various state transitions — such as new, ready, running, waiting, and terminated — as it is scheduled and executed by the operating system. Processes may communicate through inter-process communication (IPC) mechanisms and share resources under the supervision of the operating system to ensure synchronization, security, and efficient system performance.

Operating systems manage processes to achieve efficient multitasking and resource sharing. Each process is assigned a unique Process Identifier (PID) and structured data called the Process Control Block (PCB), which contains essential information like the process state, CPU register contents, program counter, memory management information, and scheduling details. This management allows multiple processes to run concurrently while maintaining isolation and security between them.

The OS uses process scheduling algorithms to allocate CPU time efficiently among processes, ensuring that they are executed in a timely and optimized manner. Scheduling algorithms include techniques like First-Come, First-Served (FCFS), Shortest Job Next (SJN), and Round Robin (RR). Additionally, concepts like context switching—which involves saving the current state of a running process and loading another—are critical for handling multiple processes simultaneously. Effective process management is essential for responsive, stable, and efficient computing systems.