Create middleware with php artisan make:middleware followed by a class name. Laravel generates the class in app/Http/Middleware, where its handle method receives the request and the next callback.

The handle method can inspect the request, add behavior, return an error or redirect, or call the next callback to continue. After creating it, register it globally, add it to a middleware group, or assign it an alias and apply it to routes. In modern Laravel applications, middleware configuration is commonly managed in bootstrap/app.php.