A dialog is an equal exchange of information in real time between two partners or devices. Each dialogue has a beginning, a series of actions and an end. If one of the partners is a human being and the other is a computer, then the dialogue takes place through the input of commands, by pressing keys or clicking the mouse, and the output is usually via a screen
.The dialogue takes place in a question-answer alternation, with the computer taking the active part and controlling the dialogue. This is particularly evident when working with dialog boxes
, where the computer requests certain input and often only wants the following question answered when a corresponding entry is made. In general, the person making the input can follow each individual entry on the screen and thus modify or terminate his dialog part if necessary. For certain applications such as printing, authentication, saving files, and many more, there are predefined dialog boxes that limit the input options to meaningful entries.