Have you ever worked with an application that did not inform you of a warning or did not alert you of something? If not, take the following example into consideration. Imagine an e-mail client that does not inform you that you have new e-mail. How annoying would that be? Alerting users of important issues or choices that need to be made is an integral part of any user experience. A few examples of where you might want to use a dialog box to inform the user of a message and/or to have the user perform an action are as follows:
Although this is not a comprehensive list, it does give you an inkling of what is possible with dialog boxes.
The Android system has a framework built around dialog boxes that enables you to provide any implementation that you may need.
Various types of dialog boxes are available, including these, the most common: