How to understand aperture priority mode and speed priority mode in photography

What are shutter priority and aperture priority? When is aperture priority? When is the shutter priority?

Shutter priority is a function to control the motion of the subject, and it is convenient to capture the solidification effect of fast moving objects and the motion blur effect of moving objects with a low-speed shutter.

Aperture is preferentially used to control the depth of field, which can achieve the effect that the real background of the subject is blurred and the front and rear objects are relatively clear.

The organic cooperation of aperture and shutter is the guarantee of correct exposure. If one variable changes (aperture or shutter), the other variable will also change. Aperture priority is to control the aperture manually, so that the shutter can automatically cooperate. Aperture is one of the three major factors that control the depth of field, with large aperture (small value) and small depth of field. In order to effectively control the depth of field, aperture is the first choice. To shoot a high-speed moving subject, you should use a high-speed shutter, that is, the shutter takes priority, otherwise it will be empty.