The document discusses key concepts in determining the reach and frequency of advertising campaigns, including: 1) Reach refers to the unduplicated number or percentage of different people exposed to an ad at least once within a given time period, while frequency is how often each person is exposed. 2) There is an inverse relationship between reach and frequency - campaigns can aim for high reach with low frequency or low reach with high frequency. 3) The product of reach and frequency equals gross rating points (GRPs), which is a common benchmark for measuring campaign exposure. Budget, GRPs, reach, and frequency must be balanced.