I never see deferred in an ajax call why?

$("#myform").submit(function(event) {
    event.preventDefault();
    var val = $(this).find('input[type="text"]').val();

    // I like to use defers :)
    deferred = $.post("http://somewhere.com", { val: val });

    deferred.done(function () {
        // Do your stuff.
    });

    deferred.fail(function () {
        // Handle any errors here.
    });
});

So why not use in .ajax the deferred just in another case? Or can use in .ajax too?

Thanks!