Select some of this text then drag it over the textarea below. This should turn red as you start to drag, green as you are dragging, and blue when you let go

For elements (except images) to detect the drag event, you must select some text first. Only certain elements, such as the body or text inputs, can detect the drop event. ondrop (and other related events) can only be detected if ondragstart is detected first

Drag-drop is not part of any standard and is only available in Internet Explorer on Windows as a scripting extension. (Internet Explorer on Mac detects ondragstart only, making it unusable.) Standards compliant browsers such as Opera, Mozilla/Firefox/Netscape6+, Safari/OmniWeb, Konqueror, ICEbrowser, Escape, etc, will not support this at all. Netscape 4 (only) also detects ondragdrop, but that is completely unrelated - it can only be used to detect desktop/folder icons being dropped onto the window, and requires elevated security privileges to read the filenames that were dragged (try it on this page).