Middleware functions are the building blocks of an Express application's logic pipeline.
1How it Works
When a request hits your server, it goes through a stack of functions. Each function can perform tasks like executing code, making changes to the request/response objects, ending the cycle, or calling next().
2Global vs Local
You can apply middleware globally to every request using app.use(), or locally to specific routes. This is perfect for features like authentication, where you only want to protect certain endpoints.
3Third-Party Middleware
The Express ecosystem is huge. You can easily add features like cookie parsing, CORS support, or request logging by installing and mounting community-built middleware.
