The health communications field has been rapidly changing over the past two decades. It has evolved from a one-dimensional reliance on public service announcements to a more sophisticated approach which draws from successful techniques used by commercial marketers, termed "social marketing." Rather than dictating the way that information is to be conveyed from the top-down, public health professionals are learning to listen to the needs and desires of the target audience themselves, and building the program from there. This focus on the "consumer" involves in-depth research and constant re-evaluation of every aspect of the program. In fact, research and evaluation together form the very cornerstone of the social marketing process. Social marketing was "born" as a discipline in the 1970s, when Philip Kotler and Gerald Zaltman realized that the same marketing principles that were being used to sell products to consumers could be used to "sell" ideas, attitudes and behaviours. Kotler and Andreasen define social marketing as "differing from other areas of marketing only with respect to the objectives of the marketer and his or her organization. Social marketing seeks to influence social behaviours not to benefit the marketer, but to benefit the target audience and the general society. Like commercial marketing, the primary focus is on the consumer--on learning what people want and need rather than trying to persuade them to buy what we happen to be producing. Marketing talks to the consumer, not about the product. The planning process takes this consumer focus into account by addressing the elements of the "marketing mix."