use Illuminate\Support\Facades\Validator; Validator::extend('phone', function ($attribute, $value, $parameters, $validator) { return preg_match('/^\d{10}$/', $value); }); // Then we can use this rule in our validation rules $rules = [ 'phone_number' => 'required|phone' ];Here, we have defined a custom validation rule named `phone`. The closure passed to the `extend()` method defines the logic for this rule. In this example, we are using a regular expression pattern to check if the phone number is valid. This is just one example of how you can use the `extend()` method to add custom validation rules to your Laravel application. The `Validator` facade provides many more methods and options for creating sophisticated validation rules and messages. Overall, the `Validator` facade is a powerful package library that helps you create robust and reliable validation in your Laravel application.