Gross rating point, commonly referred to as GRP, is a metric used in advertising to measure the reach and frequency of a specific media campaign. It is calculated by multiplying the percentage of the target audience reached by the number of times the ad is aired or displayed. In simpler terms, it is a way to gauge the overall impact of an advertising campaign by taking into account both the number of people reached and the number of times they were exposed to the ad. GRPs are often used to determine the effectiveness of a campaign and to make informed decisions about future advertising strategies.