Why double underscore (__) in php?

Question

Here are many functions with double underscores before the name:

__construct, 
__destruct, 
__call, 
__callStatic, 
__get, 
__set, 
__isset, 
__unset, 
__sleep,          


        

Answer 1

As stated here:

PHP reserves all function names starting with __ as magical. It is recommended that you do not use function names with __ in PHP unless you want some documented magic functionality

Long story short, PHP calls these functions implicitly and you shouldn't use this naming convention yourself.