jQuery.noConflict()
Many JavaScript libraries use $ as a function or variable name, just as jQuery does. In jQuery's case, $ is just an alias for jQuery, so all functionality is available without using $. If we need to use another JavaScript library alongside jQuery, we can return control of $ back to the other library with a call to $.noConflict():
<script type="text/javascript" src="other_lib.js"></script>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">
  $.noConflict();
  // Code that uses other library's $ can follow here.
</script>
This technique is especially effective in conjunction with the .ready() method's ability to alias the jQuery object, as within callback passed to .ready() we can use $ if we wish without fear of conflicts later:
<script type="text/javascript" src="other_lib.js"></script>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript">
  $.noConflict();
  jQuery(document).ready(function($) {
    // Code that uses jQuery's $ can follow here.
  });
  // Code that uses other library's $ can follow here.
</script>
If necessary, we can free up the jQuery name as well by passing true as an argument to the method. This is rarely necessary, and if we must do this (for example, if we need to use multiple versions of the jQuery library on the same page), we need to consider that most plug-ins rely on the presence of the jQuery variable and may not operate correctly in this situation.
Examples:
Example: Maps the original object that was referenced by $ back to $.
jQuery.noConflict();
// Do something with jQuery
jQuery("div p").hide();
// Do something with another library's $()
$("content").style.display = 'none';