Confused about app.vue & index.vue when using nuxt

I'm new to Nuxt and got confused about when to use app.vue or /pages/index.vue .When do I use either of them or what is the purpose of using index.vue if the starting point is app.vue? .

Comments

[Luca Argentieri]

With Nuxt 3, the pages/ directory is optional. If not present, Nuxt won't include vue-router dependency. This is useful when working on a landing page or an application that does not need routing.

Doc Link: v3.nuxtjs.org/guide/directory-stru...