---
title: File-system conventions
description: API Reference for Next.js file-system conventions.
url: "https://nextjs.org/docs/15/pages/api-reference/file-conventions"
version: 15.5.15
lastUpdated: 2025-04-24
prerequisites:
  - "API Reference: /docs/15/pages/api-reference"
---



- [instrumentation.js](/docs/15/pages/api-reference/file-conventions/instrumentation)
  - API reference for the instrumentation.js file.
- [Middleware](/docs/15/pages/api-reference/file-conventions/middleware)
  - Learn how to use Middleware to run code before a request is completed.
- [public](/docs/15/pages/api-reference/file-conventions/public-folder)
  - Next.js allows you to serve static files, like images, in the public directory. You can learn how it works here.
- [src Directory](/docs/15/pages/api-reference/file-conventions/src-folder)
  - Save pages under the `src` folder as an alternative to the root `pages` directory.

---

For an index of all available documentation, see [/docs/15/llms.txt](/docs/15/llms.txt)