Process Control Block

A process in an operating system is represented by a data structure known as a process control block (PCB) or process descriptor. The PCB contains important information about the specific process including

• The current state of the process i.e., whether it is ready, running, waiting, or whatever.
• Unique identification of the process in order to track "which is which" information.
• A pointer to parent process.
• Similarly, a pointer to child process (if it exists).
• The priority of process (a part of CPU scheduling information).
• Pointers to locate memory of processes.
• A register save area.
• The processor it is running on.

The PCB is a certain store that allows the operating systems to locate key information about a process. Thus, the PCB is the data structure that defines a process to the operating systems.