$(document).ready(function() {
      //move he last list item before the first item. The purpose of this is if the user clicks to slide left he will be able to see the last item.
      $('#carousel_ul li:first').before($('#carousel_ul li:last')); 
      
      
      //when user clicks the image for sliding right        
      $('#right_scroll img').click(function(){
      
          //get the width of the items ( i like making the jquery part dynamic, so if you change the width in the css you won't have o change it here too ) '
          var item_width = $('#carousel_ul li').outerWidth();
          
          //calculae the new left indent of the unordered list
          var left_indent = parseInt($('#carousel_ul').css('left')) - item_width;
          
          //make the sliding effect using jquery's anumate function '
          $('#carousel_ul:not(:animated)').animate({'left' : left_indent},500,function(){    
              
              //get the first list item and put it after the last list item (that's how the infinite effects is made) '
              $('#carousel_ul li:last').after($('#carousel_ul li:first')); 
              
              //and get the left indent to the default -210px
              $('#carousel_ul').css({'left' : '-640px'});
          }); 
      });
      
      //when user clicks the image for sliding left
      $('#left_scroll img').click(function(){
          
          var item_width = $('#carousel_ul li').outerWidth();
          
          /* same as for sliding right except that it's current left indent + the item width (for the sliding right it's - item_width) */
          var left_indent = parseInt($('#carousel_ul').css('left')) + item_width;
          
          $('#carousel_ul:not(:animated)').animate({'left' : left_indent},500,function(){    
          
          /* when sliding to left we are moving the last item before the first list item */            
          $('#carousel_ul li:first').before($('#carousel_ul li:last')); 
          
          /* and again, when we make that change we are setting the left indent of our unordered list to the default -210px */
          $('#carousel_ul').css({'left' : '-640px'});
          });
          
          
      });
});