How should the keywords extends and implements be used in PHP classes to extend functionality?

When we want to extend the functionality of a class in PHP, we can use the "extends" keyword to create a subclass that inherits properties and methods from a parent class. If we want to implement interfaces in a class, we can use the "implements" keyword to specify which interfaces the class should adhere to. By using these keywords, we can easily extend and implement additional functionality in our PHP classes.

// Parent class
class ParentClass {
    // Properties and methods
}

// Subclass extending ParentClass
class SubClass extends ParentClass {
    // Additional properties and methods
}

// Interface
interface MyInterface {
    // Method declarations
}

// Class implementing MyInterface
class MyClass implements MyInterface {
    // Method implementations
}