In this tutorial, we will build a caching plugin for WordPress from scratch. We will start by creating a settings page in the WordPress admin, where we can enable or disable the caching functionality. Next, we will add hooks to cache the page and save the cached output to disk. We will also add a method to clear the cache and display a link in the admin top bar menu. Finally, we will modify the caching functionality to only run when users are not logged in, to prevent cached content from being displayed to logged-in users. By the end of this tutorial, you will have a caching plugin that can improve the performance of your WordPress site.