Explanation:
The Process Control Block (PCB) is a crucial data structure in operating systems that stores essential information about a process. It allows the operating system to manage and control processes effectively. Every process in the system is associated with a unique PCB that holds its operational metadata.

The PCB contains several fields such as the process ID (PID), process state (ready, running, waiting), program counter (address of the next instruction), CPU registers, memory management information, accounting data, and I/O status information. This structured data helps the OS efficiently manage multiple processes simultaneously.

The PCB plays a central role during context switching. When the CPU switches from executing one process to another, the current process’s state is saved in its PCB, while the new process’s state is loaded from its PCB.

Formal Definition:
A Process Control Block (PCB) is a data structure used by the operating system to store essential information about a process, including its state, resources, and scheduling details, enabling efficient process management and control.

Additional Information:
PCBs are usually organized into a process table maintained by the operating system. This table allows quick access and efficient management of process-related information. The data stored in a PCB ensures process isolation and proper scheduling.

During process creation, a new PCB is generated, and all relevant fields are populated. Similarly, when a process terminates, its PCB is removed from the process table. Without PCBs, multitasking operating systems would face challenges in process control and resource allocation.