Small continious wave radars are using the Doppler phenomena. Even the most simple door opener is able to detect the changes in the reflected signal caused by the Doppler shift. There are many other practical uses of the doppler shift from the medical imaging up to the astronomy.
The Doppler shift can be observed e.g. with a car’s horn. When the horn is approaching, it will sound with higher pitch which means higher frequency and shorter wavelength. By a receding horn you will hear a lower pitch which refers to a lower frequency and longer wavelength.