Explain the concept of middleware chaining in Express.js and how it can be used to implement request-level authentication and logging.

Middleware chaining in Express.js refers to the sequential execution of middleware functions in the order they are defined. Each middleware function has access to the request object (`req`), the response object (`res`), and the `next()` function. The `next()` function is crucial; it's what allows the request to proceed to the next middleware in the chain. A middleware function can perform actions on the request or response, modify them, terminate the request-response cycle, or pass control to the next middleware by calling `next()`. Middleware ch....