Wikipedia defines social marketing:
“Social marketing is the systematic application of marketing, along with other concepts and techniques, to achieve specific behavioral goals for a social good. The primary aim of social marketing is ‘social good’, while in ‘commercial marketing’ the aim is primarily financial.”
According to Weinrich Communications:
“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 behaviors. 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 behaviors not to benefit the marketer, but to benefit the target audience and the general society.’”
Social marketing, then, is communicating with people to present an idea that may benefit them as opposed to trying to sell them a product that will financially benefit its creator. That is not to say that a product or idea or behavior cannot benefit both the marketer and the recipient; certainly it can. And actually the best ideas and products out there do just that!