As like as other programming languages, like, Java, the final keyword is added into PHP as of its version 5. This keyword is used as a modifier, but only applicable for PHP classes and functions.

The final keyword is used to prevent a class from being inherited and to prevent an inherited method from being overridden.

Example
The following example prevents inheritance of a class using the final keyword:

<?php
final class MyClass {
 public $website = "Slight Book";
}

// This code will throw an error
class AnotherClass extends MyClass{};
?>