Modal window
In user interface design, a modal window is a graphical control element subordinate to an application's main window which creates a mode where the main window can't be used. The modal window is a child window that requires users to interact with it before it can return to operating the parent application, thus preventing the workflow on the application main window. Modal windows are often called heavy windows or modal dialogs because the window is often used to display a dialog box.
Modal windows are commonly used in GUI systems to command user awareness and to display emergency states, although they have been argued to be ineffective for that use. Modal windows are prone to produce mode errors.
On the Web, they are often used to show images in detail, such as those implemented by Lightbox library.
Relevance and usage
Use cases
Frequent uses of modal windows include:
Drawing attention to vital pieces of information. This use has been criticized as ineffective because users are bombarded with too many dialog boxes, and habituate to simply clicking "Close", "Cancel", or "OK" without reading or understanding the message.