This is a common problem when using multiple JavaScript libraries as many of them define $()

SharePoint is using ASP.NET Ajax so if you include JQuery you should do that in noConflict mode.

This is a common problem when using multiple JavaScript libraries as many of them define $()

SharePoint is using ASP.NET Ajax so if you include JQuery you should do that in noConflict mode.

You turn that on using

jQuery.noConflict();

Now $ will never mean jQuery unless you use constructs like:

jQuery(document).ready(function($){
    /* code using $ */ 
});

or

(function($) {
    /* code using $ */ 
})(jQuery);