In svelte, you define components in a file.

This is a special file extension that allows you to add your script, style and template all in one place. You’ll see how a counter component will hold state in Svelte as well as interact and style that component through the different parts of the file.

We'll implement the classic counter example that will show you how to update component state.

You can do a deep dive on Svelte with Tomasz Łakomy’s Up and running with Svelte 3