Occasionally we still encounter the odd person who has no idea what graphic design actually is. The way we like to describe it, is as a place where two very different disciplines collide.
From one direction we have art, which exists to stimulate and promote/provoke thought. From the other is design, which is the process of creating something that physically works, whether it be an engine, a bridge or whatever. Decent graphic design is to combine art and design to deliver a communication that successfully achieves a desired response.
Logos and Stationery, brochures and catalogues, leaflets and flyers, infographics and diagrams. These all rely on the above.