Can anyone explain what the jquery documentation is exactly referring to with this statement: "the argument to write failsafe jQuery code using the $ alias, without relying on the global alias" when referring to using the following:

    jQuery(function($) {
});

I have been using jquery for a while now so understand what this code is doing to a certain extent but the phrase used in the documentation about writing failsafe jquery code puzzles me and i am unsure whether it is important or not.