Since it is used to track process information, the PCB plays a key role in context switching.
In multitasking operating systems, the PCB stores data needed for correct and efficient process management.
[4] Though the details of these structures are system-dependent, common elements fall in three main categories: Status tables exist for each relevant entity, like describing memory, I/O devices, files and processes.
I/O tables may have entries stating the availability of a device or its assignment to a process, the status of I/O operations, the location of memory buffers used for them, etc.
This includes: PCB must be kept in an area of memory protected from normal process access.