The whole business of marketing is, in large measure, about controlling the perceptions of a product in the marketplace using all available means...from the obvious and visible ones like advertising and public relations to the more subtle ones such as pricing or distribution.
Savvy marketers develop their marketing strategy based on the target audience who will buy their product, the unique difference of the brand and the conditions of the marketplace. Communications strategy, on the other hand, is based on perceptions--the feelings and emotions--they want a prospect to carry away.
Advertising is a combination of art and science; the art is in taking the main marketing message and creating a framework which touches the emotions to make it memorable. Years, indeed decades, of studying how people take in information has taught us that decisions as subtle as the choice of colors, typeface and placement of elements on a page can have as much to do with the impression a prospect is left with as the words in the headline or text.
The science is in the demographics, the media, the market research. Success is in making a good marriage of the two.