PHP oops concept : One of the main advantages of object-oriented programming is the ability to reduce code duplication with inheritance, code duplication means reduces same function/method write multiple time.code duplication occurs when same code write more than one. In inheritance we have one parent class and other is child class, parent class having properties can access child class. Code : https://drive.google.com/open?id=0BxmTZPVcu72fbUJaS3lCQUVvYmM Demo: http://freeteachnology.hol.es/Inheritance/ How to create classes? In order to create a class, we group the code that handles a certain topic into one place. For example, we can group all of the code that handles the users of a blog into one class, all of the code that is involved with the publication of the posts in the blog into a second class, and all the code that is devoted to comments into a third class. Syntax: class <Class-name>() { //write something code::- } Eg: class MyCo...