A target rating point (TRP) is a metric used in marketing and advertising to compare target audience impressions of a campaign or advertisement through a communication medium relative to the target audience population size. In the particular case of television, a device is attached to the TV set in a few thousand viewers' houses to measure impressions. These numbers are treated as a sample from the overall TV owners in different geographical and demographic sectors. Using a device, a special code is telecasted during the programme, which records the time and the programme that a viewer watches on a particular day. The average is taken for a 30-day period, which gives the viewership status for the particular channel. This has an average limit between 0-3.0.