The Data Source is a crucial part of Tableau. Of course, the purpose of the tool is to visualize data, but without Data Source, there's no visualization. The Data Source is the engine of Tableau. It affects the performance, the quality of the analysis, the speed, and more. Also, like any engine, it's necessary to spend some time taking care of it. 

In this chapter, you'll learn how to build the best possible engine for your analysis. We will cover the following topics:

• Understanding the Data Source
• Refreshing a Data Source and dealing with changes
• Field customization and default properties
• Hierarchies 
• Groups, Sets, and Bins

Let's start with a clear explanation of what a Data Source is.