In computer program development, a panel is a representation of what information will be sent to a user's display screen in given circumstances. Typically, when designing a program, the user interface is specified by portraying what information (text and pictures) will be presented to the user at different stages of using the program. For example, each menu, help page, or other form of content constitutes a panel of information that is to be implemented by developers and tested by early users. Since most applications are developed against the context of an operating system graphical user interface ( GUI ), these elements can sometimes be assumed in describing specific panels. Generally, in a windowed user interface, a panel is designed for each window of information.