A dialog box is a box, window, or message that is displayed on the monitor of a computer to communicate something to the user. These boxes often appear as alerts or warnings to a computer user that he or she is about to do something that may have negative consequences, such as close a program without saving information in it first. A dialog box may also appear to make a computer user aware that something has happened, which he or she may not otherwise be aware of, and to ensure communication between the computer software and user.
Depending on the computer operating system (OS) that is running on a computer, a dialog box can appear in a number of different ways, though they are typically fairly similar. The box will usually appear as a separate window or pop-up. A dialog box is part of the graphical user interface (GUI) of a computer system or OS and allows the OS to communicate information to the computer user.
The type of information communicated through a dialog box, and the type of box used, often depends on a particular situation. In general, information communicated through such a box informs a computer user that a particular event has transpired or will do so soon. For example, if someone closes a program but has not yet saved information in that program, a box will typically appear to warn a user that the information will be lost unless he or she saves. A dialog box may also appear if a program terminates suddenly, often called crashing, to make the user aware that the termination has occurred and to give any error information possible to the user.
There are two basic types of dialog boxes: modal and modeless. Either one will typically require some type of input from a user before it will disappear, such as confirmation by the user of seeing the box or a selection of one of several options. A modal dialog box stops the program that is related to the message appearing on the box from continuing to progress, and the user cannot interact with that program while the box is present. For example, if someone closes a program without saving, a modal box would appear to warn the user about the loss of data, and this would stop the program from continuing with its closure until the user confirms the action using the box.
A modeless dialog box, on the other hand, does not alter how a program is running and so the program can continue its operations. This could occur if a program is performing a lengthy task, such as copying information or rendering a complicated scene in a graphics program. Such modeless boxes may allow the computer user to cancel or alter the task, though the presence of the box does not hinder that task.