Describe the basic elements of a feedback control loop.

A feedback loop has: Process - the system being controlled, Sensor/Transmitter - measures the controlled variable and sends signal, Controller - compares measurement to setpoint and calculates output, Final Control Element - implements control action (typically a valve), and Setpoint - desired value of controlled variable. Information flows: measurement to controller, controller calculates error (SP - PV), applies control algorithm, sends output to final element, which affects the process. The loop continuously adjusts to maintain setpoint.