In jQuery, what does $.fn. mean?
It allows you to extend jQuery with your own functions.
For example,
$.fn.something = function{}will allow you to use
$("#element").something()$.fn is also synonymous with jQuery.fn which might make your Google searches easier.
This has been covered in some detail here:
Why jQuery do this: jQuery.fn.init.prototype = jQuery.fn?
But the short of it is that $.fn is an alias for $jQuery.prototype