[jQuery] $.ajax ?

[Danjojo]

Before I use the $.ajax function, do I need to install a codebase for
it?

I notice it is similar to Klaus Hartl cookie plugin, where I install
his codebase, then use it later like var country =
$.cookie('language');

When I start to use this code it seems almost like the rest of the
working jQuery portions of the web page stop working.
        $.ajax({
                url: "language_sheet_en.xml",
                dataType: "xml";
                success: function(xmlDocument){
                        $(xmlDocument).find(...).dosomeThing(...);
                }
        });

Do I need to install an ajax library or is it allready available in
my
jQuery build:  * jQuery 1.1.3.1


Thank you.