Description: Application-level middleware in web frameworks like Express.js refers to functions that execute during the lifecycle of an HTTP request in an application. These functions can modify the request and response, end the request, or call the next middleware function in the stack. This type of middleware is essential for building web applications, as it enables the implementation of features such as authentication, error handling, data validation, and session management. Being tied to an application instance, application-level middleware can be applied to all routes or specific routes, providing flexibility in configuring the application’s behavior. Additionally, it allows for code modularization, making reuse and maintenance easier. In summary, application-level middleware is a powerful tool that helps developers build robust and scalable web applications in various contexts.
