About Scenarios

I was reading about scenarios in the official guide and I didn’t understand this line:

"By default, the scenarios supported by a model are determined by the validation rules declared in the model. However, you can customize this behavior by overriding the yii\base\Model::scenarios() method"

The above means that I can declare scenarios in two differents ways? In the rules() method and in the scenarios() method?

Thanks in advance :)