Yii 2.0 requires PHP 5.4.0 or above and runs best with the latest version of PHP 7. You can find more detailed requirements for individual features by running the requirement checker included in every Yii release.
Using Yii requires basic knowledge of object-oriented programming (OOP), as Yii is a pure OOP-based framework. Yii 2.0 also makes use of the latest features of PHP, such as namespaces and traits. Understanding these concepts will help you more easily pick up Yii 2.0.
