On Screen Display (OSD) is a method by which an image or message can be superimposed on the displayed screen of the device.
Typically, the service provider sends OSD messages to the customer Set Top Box or Smart Card through corresponding Conditional Access System (CAS). Such messages are flashed on the customer TV set for a specified duration.
The operator at the service provider's place can set the display duration of the OSD messages before sending such messages to the Set Top Box.