It's not "start" is an alias to "explorer", it's that "start" runs the args through "ShellExecute".

I mention this only because it has some other uses. For instance, Windows apps can install run handlers so that something like Start->Run->Excel will launch Excel. Just running "excel" on a command prompt won't work, but "start excel" will work, since that kicks off the right path.

You can also use something like "start /w filename.txt" to start an instance of your editor, and wait for it to close (well, mostly, some apps do weird things and break this)