A special box on your screen to tell you something about what is happening - let's hope it isn't to say something is wrong
a window in which you are expected to select various options and/or enter a filename before the computer performs a particular task or operation
A way that Graphic User Interfaces (GUIs such as Windows or the Mac Desktop) use to ask us for what we want in a specific situation. For example, when you open a word processor and select open from the file menu a dialogue box will pop up so that you can specify which document you wish to open. You might then select which drive or directory (folder) to look in or what type of file you want.