What is the working principle of a high-pressure washer? How to select and use a high-pressure water gun?

A high-pressure water gun uses a power unit to drive a high-pressure plunger pump, generating high-pressure water to wash the surface of an object. The impact force of the water is greater than the adhesion between the dirt and the object’s surface, causing the high-pressure water to peel off and wash away the dirt, thus cleaning the object’s surface. So, how do you choose a high-pressure car wash water gun? How do you use a high-pressure water gun?