The difference between $this and $of this in jQuery

// this Is actually 1 a Html  Elements. 
// $this  It's just a variable name, plus $ To show that it's a jquery Object. 
//  while $(this) It's a transformation, will this The said dom Object to jquery Object, so you can use it jquery Provides method operations. 


(function($){
	$.fn.hilight = function(options){
		debug(this);

		var defaults = {
			foreground: 'red',
			background: 'yellow'
		};

		var opts = $.extend({}, $.fn.hilight.defaults, options);

		return this.each(function() {
      // this Is actually 1 a Html  Elements. 
      // $this  It's just a variable name, plus $ To show that it's a jquery Object. 
      //  while $(this) It's a transformation, will this The said dom Object to jquery Object, so you can use it jquery Provides method operations. 
			$this = $(this);

			// build element specific options
			var o = $.meta ? $.extend({}, opts, $this.data()) : opts;
			
			// update element styles
			$this.css({
				backgroundColor: o.background,
				color: o.foreground
			});

			var markup = $this.html();
			// call our format function

			markup = $.fn.hilight.format(markup);

			$this.html(markup);
		});

	};


	// define our format function
	$.fn.hilight.format = function(txt) {
		return '<strong>' + txt + '</strong>';
	};


	//  The plug-in defaults
	$.fn.hilight.defaults = {
		foreground: 'red',
		background: 'yellow'
	};

	function debug($obj) {
		if (window.console && window.console.log){
			window.console.log('hilight selection count: ' + $obj.size());
		}
	};

})(jQuery)