What is Closed Loop Operation

Closed-loop Systems use feedback where a portion of the output signal is fed back to the input to reduce errors and improve stability

Systems in which the output quantity has no effect upon the input to the control process are called open-loop control systems, and that open-loop systems are just that, open ended non-feedback systems.

But the goal of any electrical or electronic control system is to measure, monitor, and control a process and one way in which we can accurately control the process is by monitoring its output and “feeding” some of it back to compare the actual output with the desired output so as to reduce the error and if disturbed, bring the output of the system back to the original or desired response.

References:

https://www.electronics-tutorials.ws/systems/closed-loop-system.html