What is the meaning of EV value in photography? What's the use? I hope to give a detailed answer. Thank you?

Ev: (exposure value) value: exposure value. 1EV corresponds to twice the exposure ratio, which is usually called "first stop".

Exposure value is a very important skill in photography, and too high exposure will lead to a pale and unsightly picture. Underexposure will cause the picture to be too dark and unclear.

Extended data:

In photography, exposure value (EV) represents all camera aperture shutter combinations that can give the same exposure. This concept was developed in Germany in 1950s, which tried to simplify the process of choosing between equivalent shooting parameters. Exposure value can also represent a step difference on the exposure scale, and 1EV corresponds to twice the exposure ratio, which is usually called "first gear".

Exposure value was first represented by symbols. This usage continues to be used in ISO standards, but the abbreviation EV is more common in other places.

Although theoretically all exposure value's same shooting parameters will give the same exposure, they may not be able to take exactly the same photos. The exposure time (shutter speed) determines the degree of motion blur, as shown on the right. The aperture determines the depth of field.

References:

Exposure value-Baidu encyclopedia