Icons have been around for a very long time. You can probably trace back some of the original icons back in to the Egyptian hieroglyphics. And just like today, they all represent specific concepts and information. They can give you directions, highlight information, tell you what something is and in some cases, even keep you from seriously hurting yourself.
One of the many types of illustration work I am getting more calls for is for information graphics. Not just icons, but technical illustration either for instruction manuals, posters or labels. Some would say it’s dry stuff, but somehow I like the challenge of taking the engineer’s scribbles and notes and making it work into something useful and cool.