The Doppler Effect is a physics phenomenon that occurs when there is a change in frequency or wavelength of a wave in relation to an observer moving relative to the source of the wave. This effect can be observed in various situations, such as with sound waves from a moving car or electromagnetic waves from a moving star. One common example of the Doppler Effect is the sound of a siren on a passing ambulance. As the ambulance approaches, the sound waves are compressed, leading to a higher frequency and a higher pitch. Once the ambulance passes and moves away, the sound waves are stretched, resulting in a lower frequency and a lower pitch. Another example is the redshift of distant galaxies. As galaxies move away from Earth, the light waves they emit are stretched, causing a shift towards the red end of the spectrum. This phenomenon provides evidence for the expansion of the universe. Understanding the Doppler Effect allows scientists to make important observations about the motion of celestial bodies and the structure of the universe. It also has practical applications in radar technology, medical imaging, and even in the design of musical instruments. The Doppler Effect highlights the interconnectedness of physics with everyday phenomena and the broader cosmos.