Eric Parker explains the three methods for creating group options in Tableau. The three grouping options include header grouping, visual grouping and geographic grouping.
Header grouping focuses on allowing users to combine header values, which is particularly useful with bar charts. With visual grouping, the user can select data points to a group (e.g. Quadrant charts) whereas geographic grouping (e.g. Maps) is focused on the user selecting geographic entities in a group.