모든 페이지는 index.tsx가 필요하다.

_app.tsx 에서는 다음과 같은 일을 한다고 한다.

0. This file is the entry point for your Next.js application and acts as a wrapper for all your pages.

1. It allows you to define global styles, layout components

2. provide functionality that should be accessible across all pages

3. Custom error handling using componentDidCatch

4. Inject additional data into pages

5. add global CSS

   파라메터 두개 있는데 뭐에 쓰이는 물건인고?

• _index.tsx

  일종의 Landing page.

_index.tsx: This file is a specific page file that corresponds to the root URL of your application (e.g., /). It acts as the landing page or home page of your app. The name _index.tsx signifies that it is the index file for the root route.