Strange (to me) routing behaviour

Hi All,

I was hoping to get some clarification about routing.  I was under the impression that the only pages you could access were ones that were setup in the routes.php file.  Example:

URL: abc.com

Route entry: $route['hello'] = 'example/hi';

As expected, I can access the page at abc.com/hello.

Now, if i comment out that line in the code:

//$route['hello'] = 'example/hi';

I get a 404 if i try accessing abc.com/hello (which again, I expect).  What I find peculiar though is that if I enter abc.com/example/hi in my browser, I can access the content.  I didn't know that such a thing was possible.  Could someone offer me some insight (even if it's just as simple as  yes... it is possible)?

Not sure if it makes a difference but here is my .htaccess file:

RewriteEngine on
RewriteCond $1 !^(index\.php|images|robots\.txt)
RewriteRule ^(.*)$ /index.php/$1 [L]

Thanks.