Installation of Yii mainly involves the following two steps:
Tip: Yii does not need to be installed under a Web-accessible directory. A Yii application has one entry script which is usually the only file that needs to be exposed to Web users. Other PHP scripts, including those from Yii, should be protected from Web access; otherwise they might be exploited by hackers.
After installing Yii, you may want to verify that your server satisfies Yii's requirements. You can do so by accessing the requirement checker script via the following URL in a Web browser:
Yii requires PHP 5.1, so the server must have PHP 5.1 or above installed and available to the web server. Yii has been tested with Apache HTTP server on Windows and Linux. It may also run on other Web servers and platforms, provided PHP 5.1 is supported.