What is Authentication middleware in Laravel, and what role does it play in a real application?

What is Authentication middleware in Laravel, and what role does it play in a real application? In Laravel, authentication middleware should be understood as part of a larger application architecture rather than as an isolated API call. Authentication middleware can prevent unauthenticated users from accessing protected routes. A strong understanding includes its purpose, the layer where it belongs, the data or request flow it affects, and the situations where another mechanism may be more appropriate. Practical context: Middleware inspects or modifies HTTP requests and responses and is commonly used for authentication, authorization, rate limiting, logging and request-level policy. The specific focus here is authentication middleware: Authentication middleware can prevent unauthenticated users from accessing protected routes. This question is designed to test not only terminology, but also how the concept fits into Laravel's request, application, database, security, or deployment workflow.