PHP functions that start with a double underscore __ , are called magic functions in PHP.

__construct()
__destruct()
__call()
__callStatic()
__get()
__set()
__isset()
__unset()
__sleep()
__wakeup()
__toString()
__invoke()
__set_state()
__clone()
and __autoload() are the magic functions in php.

This is imperative that you recall. PHP does not provide the meanings with the secret features.
The actual designer ought to really write the particular program code that defines just what the particular secret function will work. But, secret features won't ever immediately be called with the designer, PHP will probably contact the particular function behind the particular scenes. That is why they are called magic features since they are certainly not immediately called, and they let the designer to complete a few very highly effective points.