Why should web root `/` service be placed after routers and other services?

[weezy20]

In the example for serving static files :

HttpServer::new(|| {
        App::new()
            // We allow the visitor to see an index of the images at `/images`.
            .service(Files::new("/images", "static/images/").show_files_listing())
            // Serve a tree of static files at the web root and specify the index file.
            // Note that the root path should always be defined as the last item. The paths are
            // resolved in the order they are defined. If this would be placed before the `/images`
            // path then the service for the static images would never be reached.
            .service(Files::new("/", "./static/root/").index_file("index.html"))
            // Enable the logger.
            .wrap(Logger::default())
    })

I have one question. I don't understand the reason for root path service being placed last. What is meant by "The paths are resolved in the order they are defined." and why is that a problem?

[robjtede]

The Files service uses its path argument as a prefix. Therefore / would always match incoming requests and /images would never get hit. This way, /images is tried and either matches or falls back to /.