What is PCB(Process Control Block)?

PCB is a data structure in the OS and it contains all the information about a process.The following information is stored in PCB;
Process ID
When OS converts a program into the process then OS assign process ID to each process.
State of the process
PCB maintains the record of the state of each process. A process can be in new, waiting, ready, running and can be in the terminated state.
Program counter
Priority of the process
Sometimes we need to assign priority to each process. For example in priority scheduling, OS developers maintain the priority for each process.
Process Privileges
PCB maintains the record of all the privileges assigned to each process. For example privileges of Read, Write, Copy etc.
Memory management information
PCB maintains the record that how much memory is available for use and how much memory is allocated to the processes etc.
I/O status information
Interprocess communication information
Sometimes a process works independently and sometimes some processes work together to achieve a big task.
Accounting information