An illustration is a picture or drawing that helps explain or decorate something, usually in a book, article, or story. When you open a picture book, the colorful images showing what's happening in the tale are illustrations. They work alongside the words to help you understand or imagine the story better.

That's exactly what good illustrations do: they light up ideas and make them easier to grasp. A science textbook might use illustrations to show how a plant grows from a seed, or how the water cycle works. A novel might include illustrations of important scenes or characters.

An illustrator is the artist who creates these images. Famous illustrators like Norman Rockwell, Beatrix Potter, and Maurice Sendak created pictures that became as beloved as the stories themselves.

The word can also mean an example that makes something clearer. A teacher might say, “Let me give you an illustration of how fractions work in real life,” and then explain how cutting a pizza into slices demonstrates the concept. In this sense, an illustration makes an idea concrete and understandable, whether through a picture or a well-chosen example.