get_magic_method.php

<?php

class User
{
    public $firstName = 'Bob';

    protected $attributes = [
        'firstName' => 'Anto',
    ];

    public function __get($key)
    {
        return $this->attributes[$key];
    }
}

$normalUser = new User;
$normalUser->firstName;

php_magic_methods.php

<?php

class MyClass
{
    public function __construct() {}

    public function __destruct() {}

    public function __call() {}

    public function __callStatic() {}

    public function __get() {}

    public function __set() {}

    public function __isset() {}

    public function __unset() {}

    public function __sleep() {}

    public function __wakeup() {}

    public function __toString() {}

    public function __invoke() {}

    public function __set_state() {}

    public function __clone() {}

    public function __debuginfo() {}
}

set_magic_method.php

<?php

class User
{
    public $attributes = [
        'firstName' => 'Anto',
    ];

    public function __set($key, $value)
    {
        $this->attributes[$key] = $value;
    }
}

$normalUser = new User;

$normalUser->firstName = 'Martanto';
$normalUser->attributes['firstName']; // Will return 'Martanto'