Middlewares play a very important part in the request-response lifecycle. The middlewares are placed between the Server and the response. The main role of middleware is to process the request in the middle before it is received by the Route Handler. These are basically functions that can access request object, response object as well as the next middleware function in the application's request-response lifecycle (Next middleware function is commonly denoted by a variable named next). If the current middleware does not end the request-response cycle, it must call next() to pass control to the next middleware function, or the request will be left hanging.