This acronym was developed by R H Colley in 1961 it stands for Defining Advertising Goals for Measuring Advertising Response. It links the advertising goals or objectives to the mental stages of the buying process:-
Unawareness – Awareness – Comprehension – Conviction – Action
Colley suggest that communications should be aimed to affect these mental stages. So communications objectives will be to create increased levels of awareness, convey specific messages about a products attributes;usage or benefits, create brand preference or to actually make a purchase or some other action.