Abstract: A system for the real time detection of an advertisement on a particular television channel or in a video stream, the development of a probability that the user of a client device such as a laptop, tablet or mobile phone (other than the device displaying the television channel or video stream, e.g. a Television) is viewing that particular television channel or video stream and the real time provision of an associated interactive digital advertisement to the user's client device, such as a laptop, tablet or smart phone. The system is composed of a series of software processes running on computer servers. Such servers comprising a microprocessor, data base, input device and output device wherein said data base comprises computer readable instructions stored in fixed memory or other digital storage system and executable by said microprocessor.