When Edward Tufte wrote his classic books on data visualization, most of it was intended for printed media. Today, you can create visualizations that use data that can be updated in real time, with dynamic interfaces that allows interaction by the user. The design guidelines for web-based visualizations are different. They can and should be dynamic and interactive. Interactive charts can pack in much more information by hiding the details, which can be requested by the user on demand. Charts are sometimes rendered as overviews or sparklines, only revealing details through strategies such as zooming and brushing.