In this lecture, we explore the concept of phase difference in simple harmonic motion and SHM as projection of uniform circular motion. We'll examine how SHM can be visualized as the projection of a point moving in uniform circular motion, highlighting the connection between angular displacement and the sinusoidal nature of oscillations. By understanding phase differences, we can better grasp the timing and relationships between multiple oscillating systems, enhancing our comprehension of wave phenomena in various physical contexts.