This seems like a straightforward question, but it’s proven to be a difficult one to answer. Even visualization researchers – people who think about the subject all day and every day – don’t have a clear definition of what visualization is. Is it synonymous with information graphics? Does visualization have to be computer generated? Does data have to be involved, or can it be abstract? The answers vary depending on who you ask.
To me, visualization is a medium. It’s not just an analysis tool nor just a way to prove a point more clearly through data.
Visualization is like books. There are different writing styles and categories, there are textbooks and there are novels, and they communicate ideas in different ways for varied purposes. And just like authors who use words to communicate, there are rules that you should always follow and others that are guidelines that you can bend and break.
For example, you should always specify what visual encodings, such as color and shape, represent; however, while three-dimensional plots are usually unhelpful, they can sometimes provide an easier connection between the abstract and physical world.
When you think of visualization as a medium rather than a monolithic tool, it’s something much more flexible that can be used for a lot of things. It’s also more exciting. You can tell stories with data through analysis, journalism, or art. Visualization can be fun or serious; it can be beautiful and emotional or barebones and to the point.
In the end, it’s still all about the data, and visualization lets you see what you might not find in a table. There are stories in the numbers, and visualization can help you find or tell them.