Use of Script Manager Question

Dear Folks,
I am new in web forms and in general in asp.Net. I have started building a web form application and I have the following question:
When I opened for first time my new project and I visited the Site.Master (actually the master page) I noticed that in the Script Manager control theare are the following entries:
As you know better than me the script manager is used in order to take advantage of the ASP.Net WebOptimization feature
<asp:ScriptManager runat="server"> <Scripts> <%--Framework Scripts--%> <asp:ScriptReference Name="MsAjaxBundle" /> <asp:ScriptReference Name="jquery" /> <asp:ScriptReference Name="jquery.ui.combined" /> <asp:ScriptReference Name="WebForms.js" Assembly="System.Web" Path="~/Scripts/WebForms/WebForms.js" /> <asp:ScriptReference Name=& ...