Final answer:
The internal data used by an OS to supervise and control processes is known as the process control block (PCB), which contains all the information necessary for the OS to manage each process efficiently.
Step-by-step explanation:
The internal data by which the OS (Operating System) is able to supervise and control the process is commonly known as the process control block (PCB). Each process in an operating system's environment is represented by a PCB, also sometimes referred to as a process descriptor. The PCB contains vital information about the process such as its state (running, waiting, etc.), program counter, CPU registers, memory management information, account information, and I/O status information.
The existence of PCBs is crucial for the OS to manage processes efficiently, allowing for operations such as context switching, where the CPU switches from one process to another ensuring multitasking. This system-level data structure is essential for maintaining the execution state of a process when it is not currently executing on the CPU. The data contained within a PCB is also used to restart a process in the same state it was before an interruption, facilitating smooth process execution and resource management.