Another important distinction to make with fields is whether a field is being used as discrete or continuous. Whether a field is discrete or continuous, determines how Tableau visualizes it based on where it is used in the view. Tableau will give a visual indication of the default for a field (the color of the icon in the data pane) and how it is being used in the view (the color of the active field on a shelf). Discrete fields, such as Region in the previous example, are blue. Continuous fields, such as Sales, are green.
In the screenshots in the printed version of this book, you should be able to distinguish a slight difference in shade between the discrete (blue) and the continuous (green) fields, but pay special attention to the interface as you follow along using Tableau. You may also wish to download the color image pack from Packt Publishing, available at: https://www.packtpub.com/sites/default/files/downloads/9781788839525_ColorImages.pdf