A modal window (also called a ‘modal dialog’ or ‘heavy window’)is a child window, dialog or popover element subordinate to an application’s main window. It creates a ‘mode’ that disables interaction with the main window while keeping it visible behind the child window. Users must interact with the modal window, even if only to close it before they return to the parent application. This provides a way for interactions to occur in a screen separate from the workflow on the main window. Often used for image galleries, login prompts or alerts. They can be ineffective due to mode errors, especially if not intentionally triggered by the user.