What is an illustration?

The Word "illusttation" has the same latin root as the Word "illuminate," which means to shed light upon. An illustration supports, reinforces and depicts the essence of a text, such as a magazine article. Conventional illustration employed techniques as processes such as drawing, painting and engraving. Photography also serves as illustration in current use. Illustration as a practice usuall falls into two categories: Commerial (sells a specific consumer product) and Editorial (sells a concept or ideology).