Evt:Object

1

I don´t understand behavior of parameter evt:Object.
Can you explane me different btw. normal parameter e.g. Number against **Object **which is used in EventListener?
Must I use name evt?
Thanks

var submitListener:Object = new Object();
submitListener.click = function(evt:Object) {
    var result_lv:LoadVars = new LoadVars();
    result_lv.onLoad = function(success:Boolean) {
    if (success) {
        result_ta.text = result_lv.welcomeMessage;
    } else {
        result_ta.text = "Error connecting to server.";
    }
    };
    var send_lv:LoadVars = new LoadVars();
    send_lv.name = name_ti.text;
    send_lv.sendAndLoad("http://www.flash-mx.com/mm/greeting.cfm", result_lv, "POST");
};
submit_button.addEventListener("click", submitListener);