Other characteristics of PHP are as follows. Also, PHP files can support other client-side scripting languages like CSS and JavaScript. The only information that the client or browser knows is the result returned after executing the PHP script on the server and not the actual PHP codes present in the PHP file.PHP codes are first executed on the server and then the result is returned to the browser. The thing that differentiates PHP from the client-side language like HTML is, that PHP codes are executed on the server whereas HTML codes are directly rendered on the browser.
GATE CS Original Papers and Official Keys.