A Group is a way to create a new Dimension that gathers different values of another Dimension. A Group is static; you need to modify it manually.

A Group is characterized by the  icon.

There are two ways to create a Group:

• Manually, with a menu, when you know in advance how to gather the values.
• Visually, in the view, when there are too many insignificant values.

Let's start by creating a Group, manually, with Sample Superstore:

1. Right-click on Sub-Category, go to Create, then click on Group.
2. A new window opens where you see the list of the values in that Dimension. In this menu, you can manage the Groups.
3. To create a new group of values, select some values and click on the Group button at the bottom. Create a group with Tables and Chairs:

4. By default, Tableau names the new group of values with a concatenation of the values. However, it's possible to rename it by clicking on the Rename button. Rename the group Desk Furniture.
5. You can add as many groups as you want here. You can also automatically create an Other group that contains every ungrouped values. When you finish, click on OK.

6. After clicking on OK, a new Dimension is created. If you didn't change the name, it is called Sub-Category (group). Your data source should look as follows:
   

7. To test the Group, create a simple visualization: double-click on Profit, then double-click on Sub-Category (group). As you can see in the following screenshot, Tables and Chairs are combined in a group called Desk Furniture: 

If you have too many values and you want to group them to reduce the number of non-important values, you can use the visual way. Let's see how to do this with Sample Superstore:

1. One a new Worksheet, double-click on Sales, then double-click on Sub-Category to create a simple visualization. 
2. Use the button in the top menu to swap and sort the values as descending. As you can see, there are five sub-categories with small numbers of sales. They are not important so we want to group them.
3. Select the five bottom values by clicking on their names in the header (do not select the bars, it's crucial), and, in the menu that appears, you can click on the Group icon to create a group. The icon is highlighted in the following screenshot:

 

4. Again, you can rename the group by editing it on the Data pane, or with a right-click on it in the View to edit the aliases. Choose your favorite way and rename the group Small Sales. The final result is displayed as follows: 

Creating a Group visually is an excellent way to reduce the number of insignificant values and help to focus on what matters. Another perfect use case is when there is a typo, and you want to combine the wrong value with the correct one.

As we said at the beginning, a Group is not dynamic. But Sets are! Let's see how to use them.