Integrated Marketing Communications (IMC) is a marketing strategy seeking to unify traditional and modern marketing strategies, so that they work together in harmony. This is enhanced when integration goes beyond the basic communications tools to include other levels of marketing such as Horizontal, Vertical, Internal, External and Data integration.
The American Marketing Association (AMA) defines integrated marketing communications as "the planning process designed to assure that all brand contacts received by a customer or prospect for a product, service, or organization are relevant to that person and consistent over time."
Basically, it is an approach to achieving the objectives of a marketing campaign, through a well coordinated use of different marketing methods that are intended to reinforce each other.