The Doppler Effect is an observed change in the frequency of any wave when the source of the wave is moving. When the source of a wave moves toward the observer, each disturbance reaches the observer in a time less than the previous disturbance one. And when the source moves away from the observer the time taken for each disturbance to reach the observer is more than the earlier one. This causes an increase in the frequency of the wave when the object and source are moving closer for a blueshift and a decrease in the frequency when the object and source are moving away from each other for a redshift. The Doppler Effect can be observed in all types of waves like sound, light, etc. One popular application of the Doppler Effect is in measuring the speed of objects.