What is object-oriented programming (OOP) and how is it implemented in PHP? Provide examples of classes, objects, and inheritance.

Object-oriented programming (OOP) is a programming paradigm that organizes code around objects, which are instances of classes. It provides a way to structure code, promote reusability, and model real-world entities. In PHP, OOP is implemented through classes, objects, and inheritance. Here's an in-depth explanation along with examples: 1. Classes: * A class is a blueprint or template for creating objects. It defines the properties (attributes) and behaviors (methods) that objects of that class will have. * In PHP, you can define a class using the `class` keyword followed by the class name. * Example: ``` php`class Car { public $brand; public $color; public function startEngine() { echo "Engine started!"; } }` ``` * In the above example, the `Car` class has two properties: `$brand` and `$....