From http://codular.com/introducing-php-classes

sample.class.php

<?php 
  class Person {    
  private $alive = true;      
  protected $gender = '';     
  protected $genitalOrgan = '';  }  


  class Man extends Person {    
  public function __construct(){        
  $this->gender = 'male';        
  $this->genitalOrgan = 'penis';     } 

} ?>