A box displayed on your PC screen by a program including a message normally indicating that something is about to happen or has just happened. The dialog box requires the user to respond to the message before continuing with what it is about to do - normally the response is in the form of a Yes or No based on the answer the program will carry out the next step or stop what it is doing. An example of this could be within an Email program - you read a message that has been sent to you you decide to delete the message. After clicking on the delete button a dialog box containing the message "Are you sure you want to remove this message from your PC ? Yes or No" may be displayed.