What is middleware in Express.js?

Thank you for posing such an insightful question. Middleware, within the context of Express.js, serves as a foundational concept that underpins much of the functionality and flexibility this framework offers. At its core, middleware is a function that has access to the request object (req), the response object (res), and the next middleware function in the request-response lifecycle of an application. This next function is commonly denoted as next in Express documentation and code examples. Middleware functions can perform a wide array of tasks such as executing code, making changes to the request and the response objects, ending the request-response cycle, and calling the next middleware function in the stack...