OBJECT-ORIENTED PROGRAMMING IN PHP PHP is a server-side scripting language, mainly used for web development but also used as a general-purpose programming language. Object-Oriented Programming (PHP OOP), is a type of programming language principle added to php5, that helps in building complex, reusable web applications. The Object Oriented concepts in PHP are: Class − This is a programmer-defined data type, which includes local functions as well as local data. You can think of a class as a template for making many instances of the same kind (or class) of object. Object − An individual instance of the data structure defined by a class. You define a class once and then make many objects that belong to it. Objects are also known as instance. Inheritance − When a class is defined by inheriting existing function of a parent class then it is called inheritance. Here child class will inherit all or few member functions and variables of a parent class. Polymorphi...