Multilevel and Multiple Inheritance in PHP :
PHP OOP does not allow multiple inheritance, it allow only multilevel inheritance.
In simple word, subclass can not extend more than one super class.
But PHP allow hierarchical inheritance, Hierarchical inheritance means child can get property of their parent and parent can get property of grand parent, so in this way child can get also some property of their grand parent.
Best example of multiple inheritance in PHPAbove code will not work in php because php does not allow multiple inheritance.
Best example of multilevel inheritance in PHPAbove example is so clear to understand, child class is extending parent class and parent class is extending grand parent.This was a very basic example to understand the concept of multilevel inheritance in php oops.