jquery.parallax.js

$window = $(window);

$('section').each(function(){
 var $this = $(this); // assigning the object
 
 var off = $this.offset().top;
 $this.data("top", off);
 
  $(window).bind('resize scroll', function() {

    	// Scroll the background at var speed
  		// the yPos is a negative value because we're scrolling it UP!								
  		var yPos = -(($window.scrollTop() - $this.offset().top) / 5); 

  		// Put together our final background position
  		var coords = '50% '+ yPos + 'px';

  		// Move the background
  		$this.css({ backgroundPosition: coords });

  }); // window scroll Ends

});