Php functions that starts with double underscore are called magic methods.These functions are not stand alone functions and are defined inside class. Php will call these functions from background means behind the scenes. It is not directly called by programmer. Magic methods in PHP are given below.
1__construct : It is basically the constructor of class.
2__autoload : It includes the class automatically without adding a very large number of include statements. It simplifies the inclusion of class in php
3 __destruct :Destructor of class.
4__set: Used to set the value.
5 __call : which gets called, if defined, when an undefined method is called on this object.
6 __sleep: is called when the object is serialised, and allows you to control what gets serialised.
7__wakeup : allows you to alter the behaviour of the unserialization of the object. Just the opposite of __sleep.
8 __clone : to make a copy of an object rather than have two variables pointing to the same actual data.