This is a pretty cool one, new to Visual Basic .NET. Notify icons let you display an icon in the status notification area of the Windows taskbar (in the indented panel at extreme right in the taskbar) called the Windows system tray. You can see a notify icon in the Windows taskbar in Figure 8.5 from the Notify Icons example on the CD-ROM. It's the one at right, next to the time. (I've created this icon myself; it's not something inherent in the notify icon control.)
To set the icon displayed for a control, you use the Icon property. You also can write code in the DoubleClick event handler so that something happens when the user double-clicks the icon. And you can make the icon appear and disappear by setting the control's Visible property.
This is a great one for processes that run in the background, and don't have their own windows, although they may be parts of applications that do display windows. Visual Basic .NET now lets you create Windows services, which run in the background and can display control panels (much like Microsoft SQL Server), and you can use notify icons to let the user open such control panels.