Explain the basic operation of a Phase-Locked Loop (PLL).

A PLL is a feedback system that synchronizes an output signal with a reference signal in both frequency and phase. Components include: Phase detector (compares reference and feedback phases), Loop filter (converts phase error to control voltage, determines dynamics), VCO (generates output frequency proportional to control voltage), and Frequency divider (in feedback for frequency multiplication). PLLs are used in frequency synthesis, clock recovery, FM demodulation, and motor speed control.