$('#<%= txtSearch.ClientID %>').autocomplete({

            source: function (request, response) {

                $.ajax({

                    type: "POST",

                    contentType: "application/json; charset=utf-8",

                    url: "WebService.asmx/GetAutoCompleteData",

                    data: "{'kwrds':'" + $("#txtSearch").val() + "'}",

                    dataType: "json",

                    success: function (data) {

                        response(data.d);

                        alert("message: " + data.toString());

                    },

                    error: function (result) {

                        alert(result);

                    }

                });

            }

        });

    }

Overall, I understand the code, but there are some certain aspects that I'm completely lost in. In the following code "function (request, response) " I understand that it created a function with two parameters, request and response. The request goes to the code behind "WebService" then the response triggers when the"asmx file" send a reply.

What I don't get here is that part "function (data) {

                        response(data.d)"

what is the (data.d) and why does it use the response as a function? I'm confused I don't get that part at all, and maybe I misunderstand the part I explained. Can someone help me please? I'm so lost here!