By default, many tools assume that .nuxt is a hidden directory, because its name starts with a dot. You can use the buildDir option to prevent that. If you do change the name remember to add the new name to your file.

• The router.js file is the generated router file that Nuxt.js generates for you when you put .vue files inside the pages folder. You can use this file for debugging for when you want to look up which routes are generated for vue-router and find out the names of a specific route.
• The router.scrollBehavior.js which is your Router ScrollBehavior
• The mixins folder has the files needed for the Nuxt $fetch method.
• The views folder contains your app template and your server error page.
• The app.js is your main application file.
• The client.js file is your client file needed for everything that happens client side.
• The index.js file bootstraps your application.
• The loading.html is the file that is used when the page is loading.
• The middleware file is where your middleware is kept
• The server.js file is all the code that is ran on the server

The .nuxt folder is part of the files needed to deploy your SSR application. It is not needed for deploying your static Nuxt.js app though because we use the dist folder for that.