What are the basic elements of a feedback control loop?

A feedback control loop consists of: Process (system being controlled), Sensor/Transmitter (measures process variable), Controller (compares PV to SP and calculates output), Final Control Element (valve, VFD - implements control action), and Signal path (4-20 mA, fieldbus connecting elements). The loop creates a circular path: controller output affects process, sensor measures result, controller adjusts based on error. Each element contributes to overall loop performance and stability.