PLL, or Phase-Locked Loop, is an electronic circuit used to synchronize an output signal with a reference signal in terms of frequency and phase. It is commonly found in various applications, such as radio, telecommunications, and computer systems, where precise signal timing is crucial. The PLL continuously adjusts its output to match the reference, making it essential for tasks like frequency modulation and demodulation. In addition to its use in communication systems, PLL is also important in clock generation for digital circuits. By stabilizing the frequency of oscillators, PLLs help maintain consistent timing across devices, ensuring reliable performance in everything from microprocessors to audio equipment.