jQuery(function($){
	$(".boo").sample().fadeOut('slow');
});

/**
 * A Basic sample plugin
 */
(function($){
	$.fn.sample = function(){
		//Return this to continue chaining after the plugin (this refers to the jQuery object)
		console.log(this);//jQuery object
		console.log(this[0]);//First selected element
		return this.each(function(i){
			var $this = $(this);//$this now refers to the current element being iterated over.
			console.log(i);//Index of current element
			console.log($this.attr('id'));//Use jQuery methods to do what you like with elements
		});
	};
})(jQuery);

Simple plugin to demonstrate how the 'this' keyword is used. Plugin also allows chaining via the 'return'

Simple jQuery plugin layout + how 'this' works

plugin, jquery

jQuery