Confirmation dialog is a dialog box

Dialog box

In a graphical user interface of computers, a dialog box is a type of window used to enable reciprocal communication or "dialog" between a computer and its user. It may communicate information to the user, prompt the user for a response, or both...

 that asks user to approve requested operation. Usually this dialog appears before a potentially dangerous operation is performed (program termination, file deletion, etc.)

Typically confirmation dialog boxes have two buttons

Button (computing)

In computing, a button is a user interface element that provides the user a simple way to trigger an event, like searching for a query at a search engine, or to interact with dialog boxes, like confirming an action.-Description:A typical button is a rectangle or rounded rectangle, wider than it is...

 (e.g. Yes / No, Confirm / Cancel) or three buttons (e. g. Save / Discard / Cancel).

Some human interface guidelines

Human Interface Guidelines

Human interface guidelines are software development documents which offer application developers a set of recommendations. Their aim is to improve the experience for the users by making application interfaces more intuitive, learnable, and consistent. Most guides limit themselves to defining a...

 recommend avoiding unnecessary confirmation dialogs. BlackBerry

BlackBerry

BlackBerry is a line of mobile email and smartphone devices developed and designed by Canadian company Research In Motion since 1999.BlackBerry devices are smartphones, designed to function as personal digital assistants, portable media players, internet browsers, gaming devices, and much more...

 and Sun Java UI guidelines recommended a confirmation button be put before a cancellation button; but a default button should not be associated with a major destructive action.