Exposure compensation, what is the principle of exposure compensation?

I just want to add what the above person said about how to compensate for the exposure of the portrait.

1. If you shoot small fresh or beautiful women, you can add one-third exposure or even one, which shows high profile. After all, beautiful women are happy things. Don't make it so dark, the tone can be high, and it's okay to expose the surrounding environment or clothes a little.

2. If you shoot heavy films, such as hard life, coal workers and working people, you can appropriately reduce the exposure.