What does a closed loop system primarily utilize for its functioning?

A closed loop system primarily utilizes a feedback mechanism to function effectively. In such systems, the output is continually monitored and compared against a desired set point or target. This information is then fed back into the system to make necessary adjustments. For instance, in a thermostat-controlled heating system, the temperature (output) is constantly measured. If the temperature deviates from the set point, the feedback prompts the system to either turn on or off the heating element to maintain the desired temperature. This continuous cycle of measurement and adjustment is what characterizes a closed loop system, enabling it to respond dynamically to changes in its environment.

In contrast, external input alone doesn't account for adjustments based on output performance, nor do open communication or static conditions provide the necessary feedback that is crucial for the adaptive functioning of a closed loop system. The essence of a closed loop system lies in its ability to use feedback to refine and regulate its processes.