from AIGA Career Guide
Suppose you want to announce or sell something, amuse or persuade someone, explain a complicated system or demonstrate a process. In other words, you have a message you want to communicate. How do you “send” it? You could tell people one by one or broadcast by radio or loudspeaker. That’s verbal communication. But if you use any visual medium at all—if you make a poster; type a letter; create a business logo, a magazine ad, or an album cover; even make a computer printout—you are using a form of visual communication called graphic design.