# Middleware  ## Metadata - Author: [[nextjs.org]] - Full Title: Middleware - Category: #articles - Summary: Middleware allows you to run code before a request is completed, making it useful for tasks like authentication. You can define Middleware in a single `middleware.ts` file, but you can organize the logic into separate files for better management. It is important to note that Middleware should not be used for direct data fetching, which should be handled elsewhere in your application. - URL: https://nextjs.org/docs/app/building-your-application/routing/middleware ## Highlights - [Use Cases](https://nextjs.org/docs/app/building-your-application/routing/middleware/#use-cases) Integrating Middleware into your application can lead to significant improvements in performance, security, and user experience. Some common scenarios where Middleware is particularly effective include: • Authentication and Authorization: Ensure user identity and check session cookies before granting access to specific pages or API routes. • Server-Side Redirects: Redirect users at the server level based on certain conditions (e.g., locale, user role). • Path Rewriting: Support A/B testing, feature rollouts, or legacy paths by dynamically rewriting paths to API routes or pages based on request properties. • Bot Detection: Protect your resources by detecting and blocking bot traffic. • Logging and Analytics: Capture and analyze request data for insights before processing by the page or API. • Feature Flagging: Enable or disable features dynamically for seamless feature rollouts or testing. ([View Highlight](https://read.readwise.io/read/01jkceww2pg4wa3dmzmfvk7nvj))