Implement a jQuery plugin method and explain this keyword
<p>I find <a href="http://docs.jquery.com/Plugins/Authoring#Summary_and_Best_Practices" rel="nofollow">a doc for writing jQuery plugin</a>. I don't quite understand the use of <strong>this</strong> keyword.Can someone implement the <code>init</code> function to make it clear?In <code>init</code> function can i use this keyword?If i use,what would it refer to?A simple example will do.</p>

<pre><code>(function( $ ){

  var methods = {
    init : function( options ) { 
      // THIS 
    },
    show : function( ) {
      // IS
    },
    hide : function( ) { 
      // GOOD
    },
    update : function( content ) { 
      // !!! 
    }
  };

  $.fn.tooltip = function( method ) {

    // Method calling logic
    if ( methods[method] ) {
      return methods[ method ].apply( this, Array.prototype.slice.call( arguments, 1 ));
    } else if ( typeof method === 'object' || ! method ) {
      return methods.init.apply( this, arguments );
    } else {
      $.error( 'Method ' +  method + ' does not exist on jQuery.tooltip' );
    }    

  };

})( jQuery );

// calls the init method
$('div').tooltip(); 

// calls the init method
$('div').tooltip({
  foo : 'bar'
});
// calls the hide method
$('div').tooltip('hide'); 
// calls the update method

$('div').tooltip('update', 'This is the new tooltip content!'); 
</code></pre>
