Each field has a data type. There are seven data types in Tableau:

• Text  (also called string)
• Number, decimal, or whole (they share the same icon)
• Date
• Date and Time
• Boolean (true or false)
• Geographic values 

When you connect to a dataset, Tableau automatically chooses a type for each column of the dataset. However, as with almost everything in Tableau, you can customize it. To change the data type, you can either click on the icon, or right-click on the field and use Change Data Type, as in the following screenshot: 

The different fields in your Data Source come from the dataset. Did you notice that some Measures and Dimensions are not from your dataset? Continue reading to learn more about the generated information.