If you have never built a Laravel application, let me take a walk-through with you from scratch - with no perceived knowledge. In this tutorial, I am going to walk through creating a new Laravel application, something of a refresh of https://laravel-news.com/your-first-laravel-application, which was posted mid-2021.
If you ask any Laravel developer why they like Laravel - almost all the time, they will say the developer experience.
As we already said, we are building a bookmarking application, so we can assume what we want this application to do.
Then the reason we can call $this->validate is because we are extending the main Controller for our Laravel application.