Briefly

1. system q[ start url ]; works because it uses the win32 start command.

   The nice thing abut this is that the start command will look up the current users preferred browser and start it with the url supplied. So, for you it may start IE, but the same command for me it would start Opera. For someone else it might start Firefox.

   For details type help start at a command window.

2. start 1, ... works because under win32, Perl has a built-in extension that does an asynchronous spawn if the first parameter to system is the magic token '1'.

   I can't point you to the documentation because I found out about it right here at PM. Probably from tye.

   Possibly here, or here or here ...