Application forms for cards usually entail agreements by the store concerning customer privacy, typically non-disclosure (by the store) of non-aggregate data about customers. The store uses aggregate data internally (and sometimes externally) as part of its marketing research. Over time the data can reveal, for example, a given customer's favorite brand of beer, or whether they are a vegetarian.
applIcatIoN fORms for CaRDs UsualLY EnTAIL aGreemENtS By the stORe concernIng CuStoMer PRIvaCy, TypicaLlY nON-disclOsure (by the sTore) of noN-Aggregate DatA aBout CuStOMeRs. the store uses aggregatE DAtA iNTernaLly (And SomeTIMes ExtERnALlY) as ParT of Its maRketing rEsEaRCh. oVeR tIME the DaTa cAN reVeaL, foR exAmPle, a givEN cusTomer's favorITE bRAnd Of bEer, OR whEthEr they are a vEgetArian.