Notifications to computer users are provided via indicators such as lights. The indicators are controlled according to rules, to convey computer-related state information to users in a consistent manner. Locations of visible indicators are chosen to facilitate easy viewing. The rules dictate colors and/or illumination pattern components that together provide users with important computer-related information. For example, colors are assigned to types of information, and illumination patterns generally to behavior-related information. Colors may be combined in various illumination patterns. In one implementation, many or all of the visible indicators may be grouped together on a single control panel from rapid viewing. Alternatively, the visible indicators may be grouped by function or other logical arrangement, such as on the keyboard and/or frame of a monitor. Alternative light sources that illuminate the system (e.g., the monitor bezel) to convey state information, instead of or in addition to individual indicators, are also described.