Svelte is a frontend component framework that can be used as an alternative to other frameworks like React or Vue. It differs from other frameworks based on how it updates the app's UI, using a compiler that converts components into highly efficient imperative code that surgically updates the DOM itself. Svelte provides instance methods to programmatically do anything you can already do via Daily Prebuilt's UI, giving flexibility to how you want to set up your own app's UI. The tutorial demonstrates how to embed Daily Prebuilt in a Svelte app, handle updating components based on whether you've joined a Daily call or not, and manage the Daily Prebuilt call with a custom control panel. It also covers how to add custom buttons to toggle local audio and clean up after leaving a Daily call.