Basic concept of Polymorphism in PHP

Polymorphism describes a pattern in object oriented programming in which classes have different functionality while sharing a common interface.

– Polymorphism is basically derived from the Greek which means 'many forms'.

– In other words, polymorphism is what join bunch of classes with one interface. 
polymorphism is a key part of php oops.

– As you can see in above image, printer class has a print method which performs multi task, such as print to screen and print to paper.
– Also, you can take example of twin brothers, they look like same but have different characters.

Here is a example which tell you about polymorphism:

class ParentClass 
{
   public function myOwnMethod() 
   {
      echo "ParentClass method called";
   }
}

class ChildClass extends ParentClass 
{
   public function myOwnMethod() 
   {
       echo "ChildClass method called";
   }
 }
 
function runClass(ParentClass $c) 
{
    $c->myOwnMethod();
}

$c = new ChildClass();
runClass($c);